《资治通鉴·汉纪·汉纪十六》
当时，担任掖庭令的张贺曾经是原太子刘据的宾客，感念太子旧恩，哀怜皇曾孙，于是小心奉养，自己出钱供给其日用，教其读书。
时掖庭令张贺，尝事戾太子，思顾旧恩，哀曾孙，奉养甚谨，以私钱供给，教书。
At that time, Zhang He, who was in charge of Yiting, had been a guest of the former Crown Prince Liu Ju. Out of gratitude for the Crown Prince's past kindness, he pitied the emperor's great-grandson, so he carefully took care of him, used his own money to provide for his daily needs, and taught him to read.