《新唐书·列传·卷一百二十七》
有时用头蘸墨汁写字。醒后自己细看，以为是神的杰作，再也写不出那么好的字。世人称他为张颠。起初，旭任常熟尉，有个老人递上状纸要求判决，第二天又来，旭讨厌他麻烦，斥责他。
初，仕为常熟尉，有老人陈牒求判，宿昔又来，旭怒其烦，责之。
Sometimes he dipped his head in ink and wrote. After sobering up, he would look at his work and think that it was the work of a god, and that he could never write anything better ever again. People called him the "Crazy Zhang". At first, Xu was an officer in Changshu. An old man came to him with a request to adjudicate a case. He came again the next day, and Xu, annoyed by his persistence, scolded him.