《资治通鉴·梁纪·梁纪五》
于谨常常骑一紫一黄两匹骏马，敕勒人都认识，他就让二人各骑一匹马冲出战阵，敕勒人以为是于谨，争着去追赶；于谨率领剩下的军队攻打追击的骑兵，敕勒人逃跑了，于谨才回到关内。
谨以常乘骏马，一紫一騧，铁勒所识，乃使二人各乘一马突阵而出，铁勒以为谨也，争逐之；谨帅馀军击其追骑，铁勒遂走，谨因得入塞。
Yu Jin often rode two horses, one was purple and the other was yellow. The Qie Le people all knew about it, so he let the two horses rush out of the battle. The Qie Le people thought it was Yu Jin, so they rushed to chase them. Yu Jin led the remaining army to attack the cavalry, and the Qie Le people fled. Yu Jin then returned to the pass.