Li Chengqian
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.