《战国策·燕三·燕太子丹质于秦亡归》
他看到秦国将要吞并六国，如今秦军已逼近易水，惟恐灾祸来临，心里十分忧虑，于是对他的太傅鞫武说： 燕秦势不两立，希望太傅帮忙想想办法才好。 
见秦且灭六国，兵以临易水，恐其祸至。太子丹患之，谓其太傅鞫武曰： 燕、秦不两立，愿太傅幸而图之。 
He saw that the Qin state was about to annex the six states, and now the Qin army was approaching Yishui, he was very worried about the disaster, so he said to his Grand Tutor Ju Wu: Yan and Qin will not stand side by side, I hope Grand Tutor can help me to think of a way.