《史记·七十列传·酷吏列传》
御史大夫公孙弘说： 我在山东当小官时，宁成做济南都尉，他处理政事就象狼牧羊一样凶。
御史大夫弘曰： 臣居山东为小吏时，宁成为济南都尉，其治如狼牧羊。
Yushi Dafu Gongsunhong said: "When I was a minor official in Shandong, Ning Cheng was the prefect of Jinan. He handled political affairs like a wolf herding sheep."