《左传·僖公·僖公二十七年》
于是晋国派郤縠率领中军，郤溱辅助他。派狐偃率领上军，狐偃让给狐毛而自己辅助他。任命赵衰为卿，赵衰让给栾枝、先轸。
乃使郤縠将中军，郤溱佐之；使狐偃将上军，让于狐毛而佐之；命赵衰为卿，让于栾枝、先轸。
So the state of Jin sent Xi Hu to lead the central army, assisted by Xi Zhen. Hu Yan was sent to lead the upper army, Hu Yan yielded to Hu Mao and assisted him instead. Zhao Sui was appointed as a minister, Zhao Sui yielded to Luan Zhi and Xian Zhen.