《左传·襄公·襄公三十一年》
郑国将要有外交上的事情，子产就向子羽询问四方诸侯的政令，并且让他写一些有关的外交辞令稿；和裨谌一起坐车到野外去，让他策划是否可行；把结果告诉冯简子，让他决定。
郑国将有诸侯之事，子产乃问四国之为于子羽，且使多为辞令。与裨谌乘以適野，使谋可否。而告冯简子，使断之。
Whenever the state of Zheng was going to conduct diplomatic affairs, Zichan would consult Zifu on the policies of feudal lords from all directions, and ask him to write diplomatic documents; he would then ask Bichen to make a plan regarding this matter, and report back to Feng Jianzi for him to make a decision.