《资治通鉴·唐纪·唐纪十五》
太宗对太子说： 李世才智有余，然而你对他没有恩德，恐怕不能够敬服你。
上谓太子曰： 李世勣才智有馀，然汝与之无恩，恐不能怀服。
Taizong said to the prince: "Li Shi had more than enough wisdom and talent, but you have no kindness to him so that I fear he could not respect you."