《新唐书·列传·卷九十一》
有一天，元甫有一疑难案件不能决断，就考一考杜佑，杜佑替他辨别真伪抓住关键，判断得没有不全面的。
它日，元甫有疑狱不能决，试讯佑，佑为辨处，契要无不尽。
One day, Yuanfu had a difficult case that he could not decide, so he tested Du You. Du You helped him to distinguish the truth from falsehood and grasp the key points, and his judgment was comprehensive.