《左传·哀公·哀公十二年》
卫出公回国，学着说夷人的话，子之当时还年幼，说： 国君必定不能免于祸难，恐怕会死在夷人那里吧！
卫侯归，效夷言。子之尚幼，曰： 君必不免，其死于夷乎！
Wei Zugong returned to his country and learned to speak the language of the barbarians. Zizhi was still young at the time and said: "The monarch will certainly not be able to escape disaster, I am afraid he will die in the hands of the barbarians!"