《旧唐书·列传·卷十七》
太宗对他说： 我的儿子刚当上太子，卿原来是他的长史，如今把宫中的事情委托给卿，所以有这样的任命。
太宗谓曰： 我兒新登储贰，卿旧长史，今以宫事相委，故有此授。
Taizong said to him: My son just became the crown prince, Qing used to be his chief clerk, and now I entrust you with the affairs in the palace, which is why I appointed you like this.