家世

按唐太宗贞观六年十一月立的《魏公先庙碑》载，魏徵祖父名魏彦，父魏长贤。魏徵夫人河东裴氏。

生平

魏徵少年时贫困，幼年丧父，家境贫寒失意却不事谋生，当了道士，以隐藏他的大志。他融会贯通于读书，见天下乱，特别留意纵横家的学说。

隋末投奔瓦岗军，成为该军将领元宝藏的书记，因为文辞优美被李密欣赏，魏徵进献十条计策给李密，李密很欣赏，但未能采用。兵败，归唐。后为窦建德所俘，建德念其才而收之。建德兵败，复归唐，拜太子洗马，事太子李建成。玄武门之变后，唐太宗以其耿直，不杀，且升谏议大夫，后迁秘书监、侍中等职，犯颜直谏太宗二百馀次。

长孙皇后派人告诉魏徵：「闻公正直，今才得实。愿公常守此志，勿少变更。」一次，李世民「得佳鹞，自臂之，望见徵来，匿怀中；徵奏事固久不已，鹞竟死怀中。」

贞观六年（632年），李世民在一次罢朝后回到内宫，怒不可遏：「会须杀此田舍翁。」长孙皇后好言劝慰太宗才免除这次灾难。十七年（643年）元月十七日，魏徵病逝。太宗悲恸之极，亲自到魏徵灵前祭奠痛哭，并罢朝五日为魏徵举哀，又命文武百官前往送葬，赠魏徵为司空，諡曰文贞，陪葬昭陵。又谓侍臣：「人以铜为镜，可以正衣冠，以古为镜，可以见兴替，以人为镜，可以明得失。朕常保此三镜，以防己过，今魏徵俎逝，遂亡一镜矣！」

魏徵虽然位居高官，但终生俭朴，家中甚至没有正堂，唐太宗得知后特地将宫中营造便殿的材料移去为他建造正堂，并赐予素屏风、素被褥、几、杖等家物。而在其过世后，其夫人遵照魏徵遗愿，婉拒太宗所赐羽葆、鼓吹等物，只以布车盛载灵柩。

魏徵生前有意将侄女嫁给王义方，王义方推辞了。但魏徵死后，王义方还是娶了魏徵的侄女。他人问起，王义方答：「以前是不想依附宰相，现在是感念知己。」

在储君问题上魏徵一直是所谓的立长派，唐太宗晚年厌弃太子李承乾，多次意欲改立魏王李泰，魏徵十分反对，因此在贞观十六年唐太宗任他为太子太师，希望由他辅佐太子，但当时魏徵已经卧病在床，上书推辞，唐太宗诏答曰：「汉之太子，四皓为助，我之赖公，即其义也。知公疾病，可卧护之」，看得出来唐太宗十分希望魏徵能以他耿直的个性改变李承乾。

唐太宗原将女儿衡山公主许给魏徵的长子魏叔玉为妻。魏徵死后，太宗亲赋诗一首，且为之树碑。魏徵生前曾向唐太宗秘密推荐当时的中书侍郎杜正伦和吏部尚书侯君集，说他们有宰相之才，但魏徵死后杜正伦获罪被罢黜，侯君集谋反被斩首，使得唐太宗怀疑魏徵实际上私下结党。唐太宗又发现魏徵生前每有谏书，必留副本于家中并且曾经出示给史官褚遂良，太宗疑此举有留为自赏及博取清名之用，大怒之下，下令推倒他亲自书写的魏徵墓的墓碑。太宗亦下旨解除婚约，衡山公主不再嫁往魏家。陈寅恪写道：「幸其事发觉于徵已死之后，否则必与张亮、侯君集同受诛戮，停婚仆碑犹是薄惩也。」

贞观十八年（644年），唐太宗亲征高丽受挫，发出了「魏徵若在，不使我有是行也」的感慨，于是又下令将毁坏的魏徵墓碑重新树立起来并慰问魏徵的遗属。

子孙

• 魏叔玉，袭郑国公爵位，官至光禄少卿

　• 魏膺，秘书丞

• 魏叔瑜，职方郎中

　• 魏华，礼部侍郎

　　• 魏瞻，驾部郎中

• 魏叔琬

• 魏叔璘

• 魏氏，嫁李元轨

魏徵孙魏殷为汝阳令，有三子：

• 魏明，监察御史

　• 魏凭，献陵台令

　　• 魏谟，字申之，唐宣宗年间宰相

• 魏隋，蓬州刺史

• 魏万，兼御史中丞

传说中的魏徵

小说《西游记》里记载了「魏徵斩龙」的故事：魏徵白天为大臣，晚上灵魂出窍，担任天庭的仙官。长安附近的泾河老龙王化身一个秀才，与一个算命先生「袁守诚」（袁天罡叔父）打赌，为了赌胜，胡乱施放雨水，犯了天条，玉帝要将他斩首，派魏徵在午时三刻监斩老龙。老龙于前一天托梦，恳求唐太宗为他说情，唐太宗满口答应。第二天，唐太宗宣魏徵入朝，并把魏徵留下来，同他下围棋。不料正值午时三刻，魏徵打起了瞌睡，梦中灵魂出窍斩了老龙。老龙阴魂不散，怨恨唐太宗言而无信，天天到宫里来捣乱，闹得唐太宗六神不安。魏徵知道皇上受惊，就派了秦琼、尉迟恭这两员大将，守在宫门保驾，果然，老龙就不敢来在前门闹了。可没过几天，那老龙又在宫殿后门来找唐太宗算帐，魏徵于是抱剑为唐太宗守后门，这样老龙才再也不敢来闹了。唐太宗体念他们夜晚守门辛苦，就叫画家画了秦琼、尉迟恭两人之像贴在宫前门口，画了魏徵画像贴于后门，结果照样管用。此举也开始在民间流传，秦琼、尉迟恭与魏徵便成了门神，双门左右贴秦琼和尉迟恭，单门贴魏徵。

籍贯的争论

历史大都记载魏徵是钜鹿人，但馆陶和晋县却记载魏徵是「钜鹿下曲阳人」。下曲阳属于钜鹿，遍观从隋朝、唐朝到今天，历代政府所设钜鹿郡的辖境都在邢台市范围。而且唐时的馆陶和晋县不属于钜鹿郡管辖，且馆陶和晋县的县志中也没有魏徵任何记载。

• 唐

吴兢《贞观政要》中记载：魏徵，钜鹿人也。近徙家相州之内黄。欧阳询书《唐京兆开元寺钟铭》碑刻铭文中记载：秘书监检校侍中钜鹿郡魏徵撰。杜淹《文中子世家》中记载：门人自远而至，河南董常、太山姚义、京兆杜淹、赵郡李靖、南阳程元、扶风窦威、河东薛收、中山贾琼、清河房玄龄、钜鹿魏徵、太原温大雅、颖川陈叔达等，咸称师，北面受王佐之道焉。

• 五代

后晋时官修的《旧唐书.魏徵本传》中记载：生于周大象庚子，名徵，字玄成，钜鹿曲城（今河北巨鹿）人。

• 宋

《太平寰宇记》中记载：魏徵钜鹿人

• 元

虞集所撰《顺德路魏文贞公宋文贞公祠堂记》说记载：魏文贞公徵，钜鹿人。王守正所编《道德真经衍义手抄》中记载：宰相魏徵，钜鹿人也。时上疏谏之。

• 明

《魏相祠记》中记载：此钜鹿为公桑梓，铜马之墟，印垄榛莽。《顺德府志》、《钜鹿县志》记载魏徵为钜鹿人

• 近代

民国时期，邢台钜鹿古城发掘出的唐代时期的魏徵祠堂和魏徵铁像也证明魏徵是邢台钜鹿人。

相关条目

• 隋末民变

• 瓦岗军

• 玄武门之变

• 贞观之治

• 唐太宗征讨高句丽

注释

• 《旧唐书·魏徵传》

• 《新唐书·魏徵传》

Background

Wei Zheng was born in 580, shortly before the founding of Sui Dynasty in 581. His family was from Julu Commandery (钜鹿, roughly modern Xingtai, Hebei). His father Wei Changxian (魏长贤) was a county magistrate during Northern Qi. Wei lost his father early in life and was poor, but had great expectations, not caring about making wealth. At one point, he became a Taoist monk. He favored studying, and as he saw that the rule of Emperor Yang of Sui was beginning to make Sui fall into a state of confusion, he particularly paid attention to strategic works.

Service under Li Mi

At the end of Emperor Yang's reign, there were many rebellions against Sui rule. One of the major ones was led by Li Mi the Duke of Wei. In 617, the secretary general of Wuyang Commandery (武阳, part of modern Handan, Hebei), Yuan Baozang (元宝藏), rebelled against Sui as well and submitted to Li Mi. He invited Wei Zheng to serve on his staff, as his secretary. Wei subsequently drafted submissions from Yuan to Li Mi, suggesting that Li Mi attack and seize nearby Wei Commandery (魏郡, also part of modern Handan) and a large food storage that Emperor Yang built, Liyang Storage (黎阳仓, in modern Hebi, Henan). Li Mi was impressed, and when he found out that Wei wrote the submissions, he requested Yuan send Wei to him. He subsequently made Wei his secretary.

In 618, Li Mi was ready for a major confrontation with the Sui general Wang Shichong, who had seized power at the eastern capital Luoyang as the regent to Sui's last emperor Yang Tong (Emperor Yang's grandson). Wei spoke with Li Mi's secretary general Zheng Ting, advocating that Li Mi take a defensive stance, refusing to engage Wang and draining Wang's food supplies. Zheng rejected the proposal, and the proposal apparently was never submitted to Li Mi. Subsequently, when Li Mi engaged Wang, Wang defeated him. Believing that he could no longer hold out against Wang, Li Mi fled to Tang Dynasty territory and surrendered to Emperor Gaozu of Tang. Wei followed him to Tang territory. Subsequently, with Li Mi's major general Xu Shiji (later known as Li Shiji) still holding the Liyang region, Wei requested that Emperor Gaozu send him to Liyang to persuade Xu to submit to Tang as well. Xu did so.

Emperor Gaozus reign

In spring 619, with Yuan Baozang being attacked by Yuwen Huaji the Emperor of Xu (who had led the coup that killed Emperor Yang in 618), Wei went to Yuan to persuade him to submit to Tang. Yuan did so. Wei apparently subsequently went back to Liyang. In winter 619, when Dou Jiande the Prince of Xia, one of Tang's major rivals, attacked and captured Liyang, Wei was among the people captured by Dou, along with Emperor Gaozu's cousin Li Shentong (李神通) the Prince of Huai'an, Emperor Gaozu's sister Princess Tong'an, and Li Shiji's father Li Gai (李盖). (Li Shiji was not captured, but several days later felt compelled to surrender to Dou as well, as his father had become a captive.) Dou made Wei his secretary.

In 621, Dou, while trying to aid Wang, under siege at Luoyang by the Tang general Li Shimin the Prince of Qin (Emperor Gaozu's son), was defeated and captured by Li Shimin. The Xia officials initially fled back to the Xia capital Ming Prefecture (洺州, in modern Handan as well) subsequently decided to surrender, and Wei followed Pei Ju back to the Tang capital Chang'an. Emperor Gaozu's oldest son Li Jiancheng the Crown Prince had long heard of Wei's talents, and he invited Wei to serve as his librarian. In 622, with Dou's general Liu Heita having risen against Tang and captured most of former Xia territory, Wei and another staff member, Wang Gui, suggested to Li Jiancheng that due to Li Shimin's accomplishments and fame, he posed a threat to Li Jiancheng, and that Li Jiancheng needed some victories of his own—indicating that he should volunteer to attack Liu. Li Jiancheng agreed, and later in 622 crushed Liu's forces. (Liu was betrayed by his own subordinate Zhuge Dewei (诸葛德威) in early 623 and turned over to Li Jiancheng; Li Jiancheng killed him.) As the brothers' rivalry intensified over the year, Wei repeatedly suggested to Li Jiancheng that he must act first and kill Li Shimin. Li Jiancheng could not resolve to do so.

In 626, however, Li Shimin, believing that Li Jiancheng would kill him, ambushed Li Jiancheng and another brother who supported Li Jiancheng, Li Yuanji the Prince of Qi, at Xuanwu Gate, killing them. He then effectively forced Emperor Gaozu to create him crown prince. He summoned Wei and rebuked him, "Why did you alienate us brothers?" Wei's colleagues were all fearful for him, but Wei, instead of begging for forgiveness, stated boldly, "If the Crown Prince had listened to my words, he would not have suffered this disaster." Li Shimin, who had been impressed with Wei himself, was further impressed by the answer, and he changed his attitude and treated Wei with respect, inviting Wei to serve on his own staff. Subsequently, when he sent Wei on a mission to pacify the eastern prefectures, Wei, believing that no one would believe Li Shimin's words that Li Jiancheng's and Li Yuanji's staff members would be spared if some of them, then under arrest, were not released, ordered them released—an act that Li Shimin was pleased with and impressed by. Later in 626, Emperor Gaozu yielded the throne to Li Shimin (as Emperor Taizong). Wei continued to serve in the imperial administration.

Emperor Taizongs reign

After Emperor Taizong took the throne, he created Wei the Baron of Julu. Later in 626, when Emperor Taizong buried Li Jiancheng and Li Yuanji with honors due imperial princes, Wei Zheng and Wang Gui requested permission to attend the funeral procession. Emperor Taizong agreed, and further ordered that all officials who served on Li Jiancheng's and Li Yuanji's staffs to attend the funeral procession.

It was said that when Emperor Taizong first took the throne, he was looking for ways to improve his reign. As he believed that Wei had great abilities in governance, he often invited Wei into his own bedroom to converse with him. Wei had the fortitude to speak up for what he saw to be right, and Emperor Taizong often gladly accepted his suggestions. In 627, when it was rumored that Feng Ang, a former Sui official who had submitted to Tang several years prior, had started a rebellion, and Emperor Taizong wanted to send forces to attack Feng, Wei advised against it, pointing out that Feng did not advance outside his own territories and appeared to be simply fearful that he had been accused of treason. Under Wei's suggestion, Emperor Taizong sent the official Li Gongyan (李公淹) to comfort Feng; Feng then showed his submission by sending his son Feng Zhidai to follow Li Gongyan to Chang'an to pay homage to Emperor Taizong. Pleased, Emperor Taizong stated, "Wei had me send a messenger, and as a result the Lingnan region was pacified, better than if 100,000 men were sent. He must receive an award." He awarded Wei with silk. Around that time, he also made Wei a deputy head of the Department of State Affairs.

Later that year, Wei was accused of nepotism. Emperor Taizong had the imperial censor Wen Yanbo investigate, and Wen found no evidence of wrongdoing. Wen nevertheless stated to Emperor Taizong, "Wei did not care about public perception or appearance of conflict of interest. Even though he had no wrongful intent, he should still be rebuked." Emperor Taizong agreed and rebuked Wei, but Wei bluntly refused to accept the rebuke, and Emperor Taizong later retracted the rebuke after concluding that Wei was correct. Throughout the rest of Wei's career, this became a pattern—that Wei would dare to speak against the emperor's opinions or acts despite Emperor Taizong's anger, and while Emperor Taizong did not accept everything that Wei said, he always treated Wei with respect.

In 629, Emperor Taizong made Wei the head of the Palace Library, but gave him the additional designation Canyu Chaozheng (参豫朝政), making him a de facto chancellor. Later that year, when the assistant censor Quan Wanji (权万纪) accused the chancellors Fang Xuanling and Wang Gui of improper selection of officials, Emperor Taizong initially ordered Hou Junji to investigate. Wei, however, pointed out that both Fang and Wang were trusted officials who should be given free rein and not have the details of their acts be picked on. Emperor Taizong agreed and cancelled the investigations.

In 630, the general Li Jing had inflicted a heavy blow to the forces of Eastern Tujue's Jiali Khan Ashina Duobi, and later that year, after Ashina Duobi was captured, Eastern Tujue chieftains submitted to Tang. Emperor Taizong requested opinions on what to do with Eastern Tujue's people. There were many different opinions, but the two opinions that Emperor Taizong appeared to consider the most were the ones by Wen and Wei, who debated extensively before Emperor Taizong. Wen argued that, pursuant to precedents of what Eastern Han Dynasty did with the Xiongnu, the Eastern Tujue people should be placed within Tang borders but organized in tribal form, to serve as a defense perimeter on the northern border. Wei advocated that the Eastern Tujue people be placed north of Tang borders, believing that they would pose a threat if placed within Tang borders. Wen, however, argued that the Eastern Tujue people could eventually be assimilated and become an asset to the Tang state, and Emperor Taizong agreed with Wen. He established 10 prefectures to settle the Eastern Tujue people and made the major chieftains the prefects, while inviting a number of Eastern Tujue nobles to serve as generals at Chang'an.

Late in 630, Qu Wentai (麴文泰), the king of Gaochang, was set to arrive at Chang'an to pay homage to Emperor Taizong. When the other Xiyu states heard this, they wanted to send emissaries as well, and Emperor Taizong initially ordered Qu's official Yanda Gegan (厌怛纥干) back to Gaochang to gather the emissaries to lead them to Chang'an. Wei advised against doing so—pointing out that if that happened, Tang would become deeply involved in Xiyu matters, and that the Tang state was not yet in a position of doing so. Emperor Taizong agreed and ordered Yanda to stop.

In 631, despite Wei's advice against it, Emperor Taizong began setting up a feudal scheme where the great contributors to Tang rule would be granted posts as prefectural prefects, to be inherited by their descendants. (Subsequently, however, due to other officials' opposition—the strongest of which came from Emperor Taizong's brother-in-law Zhangsun Wuji—Emperor Taizong cancelled the feudal scheme.)

In 632, at the urgings of many officials who believed that he should go to Mount Tai to pay homage to heaven and earth (known as Fengshan), Emperor Taizong considered doing so, but Wei opposed, and this led to a famous conversation between them, which showcased Wei's personal philosophy against overextending the state:

Emperor Taizong asked, "You oppose my conducting of Fengshan. Is it that my accomplishments were not great enough?" Wei responded, "They are great enough." Emperor Taizong asked, "Is it that my virtues were not great enough?" Wei responded, "They are great enough." Emperor Taizong asked, "Is it that China is not pacified enough?" Wei responded, "It is pacified enough." Emperor Taizong asked, "Is it that the barbaric nations have not submitted to me?" Wei responded, "They have." Emperor Taizong asked, "Is it that we have not had good harvests?" Wei responded, "We have had good harvests." Emperor Taizong asked, "Is it that signs of blessings have not occurred?" Wei responded, "They have." Emperor Taizong asked, "Then, why is it that I still cannot conduct Fengshan?"

Wei responded, "Even though Your Imperial Majesty has accomplished these six achievements, we are still inheriting the state left after the great confusion at the end of Sui rule. The population is greatly reduced and has not recovered. The food stores are still empty. When Your Imperial Majesty heads east Mount Tai, the thousands of horses and wagons require supplies everywhere they go, and it is difficult for the local government to do so. In addition, at Fengshan, the rulers and chiefs of the nations should all attend you. However, from the Yi and Luo Rivers to the Sea and Mount Dai another name for Mount Tai), there are still few villages and few people. The weeds grow thickly without end, and this would be inviting barbarians to our abdomen and showing them our weaknesses. Further, even if we greatly reward them, they would not necessarily be pleased, having come from afar. Even if you exempt the people from taxes for many years, you still cannot compensate them for their losses. Why would Your Imperial Majesty want to simply hold a great Fengshan ceremony but receive real detriments?"

Incidentally, at that time, many prefectures around the Yellow River were suffering floods, so Emperor Taizong gave up the idea.

Around the same time, there was an incident when Emperor Taizong visited his summer palace Jiucheng Palace (九成宫, in modern Baoji, Shaanxi). He sent some of his servants back to Chang'an, and they were staying at the official lodges at Weichuan County (湋川, also in modern Baoji), when the chancellors Li Jing and Wang Gui arrived. The county officials displaced the imperial servants to house Li and Wang. When Emperor Taizong heard this, he felt disrespected, and initially were going to punish the county officials. Wei disagreed, pointing out that Li and Wang were far more important and honored than the imperial servants. Emperor Taizong relented and did not punish the county officials, Li, or Wang.

Emperor Taizong was about to marry the Princess Changle to Zhangsun Wuji's son Zhangsun Chong. As the princess was born of Empress Zhangsun and was his favorite daughter, Emperor Taizong ordered that her dowry had to exceed that for his sister, the Princess Yongjia. Wei advised against it, pointing out that this was contrary to Emperor Ming of Han's observation that his sons should not be as honored as his brothers. Emperor Taizong agreed and also informed Empress Zhangsun, who was greatly impressed with Wei's honest advice, and therefore, after receiving permission from Emperor Taizong, she had her eunuchs send rewards of money and silk to Wei, praising him for his honesty. On another occasion, after Emperor Taizong returned from an imperial gathering, he was angry and yelled, "Let me find a chance to kill this farmer!" Empress Zhangsun asked whom he was referring to, and he replied, "I am referring to Wei Zheng. He always find a way to insult me in front of everyone in the imperial hall!" Empress Zhangsun retreated to her bedchambers and put on the official empress gown; standing solemnly, she prepared to bow to Emperor Taizong. He was surprised, and asked her what the reason was. She responded, "I have heard that only a most able emperor will have subordinates who have integrity. Wei shows this much integrity because you are an able emperor. How can I not congratulate you?" Emperor Taizong's anger turned to happiness, and he did not punish Wei. Soon, Wei was created a duke.

Later that year, there was an occasion when Emperor Taizong held a feast for the high-level officials at Danxiao Hall (丹霄殿), and at the feast, Zhangsun Wuji made the comment, "Wang Gui and Wei Zheng were our enemies before. I did not know at the time that we would get the chance to feast together." Emperor Taizong responded, "Wang and Wei served their master faithfully, and that was why I retained them. I do have a question: Every time that Wei gave me adverse advice and I did not accept it, then he refused to discuss the matter any further. Why?" Wei responded, "I give adverse advise only when I believe that something should not be done. If Your Imperial Majesty did not follow my advice, then if I continued to speak about it, the matter would be settled and would be done. That is why I spoke no further." Emperor Taizong responded, "You can first continue planning and then try to advise me again. What harm is there?" Wei responded, "It was written that Emperor Shun warned his officials, 'Do not obey me in my presence and make secret speeches against what I do.' If I know that something is wrong, but I continue to discuss it with Your Imperial Majesty, then I would be obeying you in your presence. That is not how Houji (后稷) and Ziqi (子弃, both legendary great officials during Emperor Shun's reign) served Emperor Shun." Emperor Taizong laughed and stated, "Everyone says that Wei is arrogant and careless, but I call him 'delicate'; this shows it."

In 633, after Wang was accused of leaking palace secrets, Emperor Taizong made Wei Shizhong (侍中) -- the head of the examination bureau of government and a chancellor post—to replace Wang. At that time, there were also a large backlog of legal matters being handled by the executive bureau, and Emperor Taizong temporarily assigned Wei to handle them. It was said that while Wei did not study law, he reasoned logically, and he was able to make proper decisions.

In 634, when Emperor Taizong wanted to send officials to visit the circuits to see how the people were doing in the provinces, Li Jing recommended Wei. Emperor Taizong, however, responded, "Wei needs to point out my faults, and I cannot let him go." Instead, he sent 13 officials, including Li Jing and Xiao Yu, out to the circuits for this mission.

Emperor Taizong had commissioned the compilation of several official histories of Tang's predecessor dynasties—commissioning Linghu Defen and Cen Wenben to compile the Book of Zhou (Northern Zhou's history); Kong Yingda and Xu Jingzong to compile the Book of Sui (Sui Dynasty's history); Yao Silian to compile the Book of Liang (Liang Dynasty's history) and Book of Chen (Chen Dynasty's history); and Li Baiyao to compile the Book of Northern Qi (Northern Qi's history). Wei was in charge of writing commentaries on a number of important persons whose biographies were contained in these histories, and after the histories were completed around 636, Emperor Taizong awarded him silk and upgraded his title to Duke of Zheng. (For reasons unclear, Wei was given credit as the lead editor of the Book of Sui, but not the other works.)

Also in 636, Wei tried to resign on account of eye illnesses. Emperor Taizong relieved him from his post as Shizhong and gave him the honorific post of Tejin (特进), but still gave him full authority as if he were still Shizhong. He also continued to designate him Canyi Deshi (参议得失), keeping him as a de facto chancellor.

By this point, Emperor Taizong had begun to favor his son Li Tai over his oldest son and crown prince Li Chengqian. When accusations were made that the high-level officials were disrespectful to Li Tai, Emperor Taizong was initially angry, rebuking the high-level officials. However, Wei responded that those high-level officials should, in fact, be more honored than the imperial princes, as the state's key personnel, and Emperor Taizong, seeing that Wei was correct, apologized.

In 637, a new code of rites, coauthored by Wei and Fang, was completed. Also in 637, Wei submitted a petition containing a number of advice for Emperor Taizong to continuously examine himself. This petition was later titled the Petition on Ten Thoughts (十思疏) and became a famous document often held up as examples of how officials should advise the emperor.

In 638, there was yet another incident where Wang, by then the minister of ceremonies, suggested that high-level officials should not have to yield to imperial princes when their processions meet. Emperor Taizong initially saw this as an insult to the imperial princes—particularly Li Tai, whom he was secretly considering replacing Li Chengqian with—and he made the statement, "Life is uncertain. If the Crown Prince should die early, how do you know that one of the princes would not be your lord in the future. How can you disrespect them?" Wei, seeing what was happening, spoke bluntly, "Ever since Zhou Dynasty, succession is always from father to son, not to brothers, to prevent plotting by younger sons and stop infighting at their origin. This is what the rulers need to be careful about." Emperor Taizong thereafter approved Wang's proposal.

In 638, Emperor Taizong, celebrating the birth of a grandson, held a feast for imperial officials, at which he made the comment:

Before I took the throne, it was by Fang Xuangling's assistance that I was able to seize power. After I took the throne, it was by Wei Zheng's assistance that I was able to have my errors corrected.

He then awarded both Fang and Wei an imperial sword. Also around that time, Wei advised him to be cognizant that he was not accepting adverse advice from others as he had previously. Emperor Taizong agreed to examine himself more carefully.

In 639, after Ashina Duobi's nephew Ashina Jiesheshuai formed a plot to ambush Emperor Taizong, but his plot was discovered and destroyed, Emperor Taizong created a Tujue prince who had served him faithfully, Li Simo (né Ashina Simo) the Prince of Huaihua, as the khan of a newly recreated Eastern Tujue state (as Qilibi Khan), and had him take the Eastern Tujue people outside of Tang territory, to be settled between Tang and Xueyantuo. At that time, Emperor Taizong made the comment that he nearly suffered because he did not listen to Wei's suggestion in 630.

In 640, after a number of years during which Qu Wentai, initially submissive to Tang, became hostile to Tang interests and had allied himself with Western Tujue, Emperor Taizong sent Hou Junji to conquer Gaochang. Qu Wentai died from illness during the siege, and his son Qu Zhisheng (麴智盛) surrendered. Wei advised that Emperor Taizong should keep Qu on the throne, as an ally—a suggestion that Chu Suiliang also spoke of—but Emperor Taizong disagreed and annexed Gaochang directly. (Emperor Taizong would later regret this in 642, when the need to station soldiers at Gaochang became more and more expensive in monetary and human costs.) When Hou's lieutenant Xue Wanjun (薛万均) was subsequently accused of raping Gaochang women, Emperor Taizong was going to hold cross-examination sessions between Xue and the alleged victims, but on Wei's urging—that whatever the results were, the empire would be harmed—Emperor Taizong cancelled the investigation.

In 641, Fang and Gao Shilian drew rebuke from Emperor Taizong when they inquired of the deputy imperial architect, Dou Desu (窦德素) of imperial construction projects — which Emperor Taizong saw as an encroachment on his liberty. However, Wei pointed out that chancellors were supposed to be responsible for all affairs of state, and Emperor Taizong, realizing that he had erred, was humbled.

In 642, Wei was ill, and Emperor Taizong and he exchanged letters with each other expressing how they missed each other, and in Wei's letters, he continued to give adverse advice to Emperor Taizong. Meanwhile, as Wei's mansion had no large halls, Emperor Taizong diverted the construction material that he was going to use for an imperial hall and constructed a hall for Wei in five days, and further awarded him with folding screens, bedding, a small table, and canes, hoping to comfort him. When Wei wrote to thank him, Emperor Taizong wrote back, stating, "I honor you for the people and the state, not for you. Why thank me?" Meanwhile, Chu, himself by now developing a reputation for offering adverse advice, was pointing out that Emperor Taizong's favors for Li Tai were creating uncertainties for officials, and Emperor Taizong, trying to stem the rumors that Li Tai would displace Li Chengqian, appointed Wei as a senior advisor to Li Chengqian. When Wei grew better, he personally went to the palace to decline, but Emperor Taizong pointed out the symbolic importance of having someone as important as himself serve as Li Chengqian's advisor, stating that even if Wei could only lie on the bed, his being named a senior advisor to Li Chengqian would help clarify the situation. Wei relented and accepted.

In spring 643, Wei was gravely ill. Emperor Taizong sent numerous messengers to attend to Wei's illness, and further had the official Li Anyan (李安俨) stay at Wei's mansion to oversee Wei's care. He also personally visited Wei, with Li Chengqian, and he pointed at his daughter Princess Hengshan and promised to give her to Wei's son Wei Shuyu in marriage. Wei died soon thereafter, and Emperor Taizong buried Wei with great honors and luxurious funeral supplies, although Wei's wife Lady Pei, pointing out that Wei was himself frugal in living, declined most of the luxuries. Wei was buried near the tomb of Empress Zhangsun (who died in 636), where Emperor Taizong would eventually himself be buried. He also commissioned a stone monument for Wei, and personally wrote the text of the monument. He missed Wei greatly and stated:

Using copper as a mirror allows one to keep his clothes neat. Using history as a mirror allows one to see the future trends. Using a person as a mirror allows one to see what is right and what is wrong. When Wei Zheng died, I lost a mirror.

Later that year, when Emperor Taizong commissioned the Portraits at Lingyan Pavilion to commemorate the 24 great contributors to Tang rule, Wei's was one of the portraits commissioned.

Later in 643, however, Li Chengqian was found to have plotted with Hou to overthrow Emperor Taizong, as he was apprehensive that Emperor Taizong would displace him with Li Tai. Emperor Taizong executed Hou and the other coconspirators, while deposing and exiling Li Chengqian (although he also blamed Li Tai's machinations for Li Chengqian's downfall and exiled him as well, creating their younger brother Li Zhi crown prince instead). As Wei had previously repeatedly recommended Hou and Du Zhenglun, a key advisor to Li Chengqian who was also exiled, as chancellor material, Emperor Taizong suspected Wei of factionalism. Also, it was discovered at the time that Wei had recorded his adverse advice to Emperor Taizong and given them to Chu, who was the imperial historian as well, displeasing Emperor Taizong further. He therefore cancelled the planned marriage between Princess Hengshan and Wei Shuyu and destroyed the stone monument that he had commissioned for Wei.

In 645, after Emperor Taizong carried out a failed attempt to conquer Goguryeo, he regretted the campaign and stated, "If Wei Zheng were still alive, he would not have allowed me to go on this campaign." He sent imperial messengers to make sacrifices to Wei and restore the stone monument, and he also summoned Wei's wife and children, greatly awarding them.

Veneration

Wei Zheng is venerated as a door god in some Chinese and Taoist temples, usually in partnership with Li Shiji.