《旧唐书·本纪·卷八》
冬十月初六，皇上命令道： 朕听政之闲暇，常看史籍，有关史事道理，实乃我留心之处，中间有什么疑难，时时须要询问。
冬十月甲寅，制曰： 朕听政之暇，常览史籍，事关理道，实所留心，中有阙疑，时须质问。
On October 6, the emperor ordered: I often read history books in my spare time, and the historical events and ideas are really what I pay attention to. I always need to ask questions when I have questions in the middle.