《资治通鉴·唐纪·唐纪五十一》
在张建封病危时，杜兼图谋替代张建封，从濠州急忙快马赶到军府，军府的僚属李藩与同事们进去问候张建封的病情，出来时，看见了杜兼，便哭泣着说： 张仆射的疾病危险到如此地步，你应当留在濠州，防止意外，现在你却丢开州城，来到这里，你打算干什么呢？
建封之疾亟也，兼阴图代之，自濠州疾驱至府。幕僚李籓与同列，入问建封疾，出见之，泣曰： 仆射疾危如此，公宜在州防遏，今弃州此来，欲何为也！
When Zhang Jianfeng was critically ill, Du Jian planned to replace him. He rushed to the military headquarter from Haozhou on a fast horse. When Li Fan, an official of the military headquarter, and his colleagues visited Zhang Jianfeng to inquire after his health, they saw Du Jian on their way out and said to him with tears on their faces, "The Assistant Minister’s health is so bad that he might die at any moment. You should have stayed at Haozhou for any eventuality, so why have you left the city and come here? What are you plotting to do?"