《新唐书·列传·卷五十五》
当初，皇帝有任崔隐甫为宰相的意思。对他说： 牛仙客很可以一起谈谈，你常见到他吗？ 
始，帝欲相隐甫也，谓曰： 牛仙客可与语，卿常见否？ 
Originally, the emperor intended to appoint Cui Yinfu as his prime minister. He said to him: Niu Xianke is someone worth talking to. Do you often see him?