《战国策·魏一·陈轸为秦使于齐》
楚王听说后，说： 李从同寡人订了约，观在燕国、齐国、赵国都把政事交给了公孙衍，公孙衍一定想为寡人做事，寡人也想任用他。 
楚王闻之，曰： 李从约寡人，今燕、齐、赵皆以事因犀首，犀首必欲寡人，寡人欲之。 
When the King of Chu heard this, he said: "Li Cong made an appointment with me, but Yan, Qi, and Zhao have entrusted Gongsun Yan with the government, so Gongsun Yan must want to do things for me, and I also want to employ him."