《汉书·传·匈奴传下》
单于听说了，派使者去命令左贤王出兵攻入乌桓，指责他们杀了匈奴使者，并攻打他们。
单于闻之，遣使发左贤王兵入乌桓责杀使者，因攻击之。
When the Chanyu heard about it, he sent an envoy to order the Left Worthy King to send troops to attack the Wuhans, accusing them of killing the Xiongnu envoy and attacking them.