《左传·僖公·僖公二十三年》
狐突回答说： 当儿子能够做官，父亲教他懂得忠诚的道理，这是古代的制度。
对曰： 子之能仕，父教之忠，古之制也。
Hu Tu replied saying: When a son is able to take a government position, his father teaches him the principles of loyalty. This is the old system.