《贞观政要·卷二·论纳谏》
从前汉文帝时，有人献千里马。文帝说： 我巡幸时每天行进三十里，打仗时每天行进五十里，仪仗走在我的前面，副车跟在我的后面，我单独骑一匹千里马，能走到哪里去呢？ 
昔汉文帝有献千里马者，曰： 吾吉行日三十，凶行日五十，鸾舆在前，属车在后，吾独乘千里马，将安之乎？ 
During Emperor Hanwen’s reign in the past, someone presented him a thousand-li horse. Emperor Hanwen said: when I go on a royal tour, I travel 30 li each day, and when I am at war, I travel 50 li each day. There is an honor guard in front of me and carriages behind me. If I ride a thousand-li horse alone, where can I go? 