《明史·列传·卷一百九十七》
陕西总督郑崇俭发兵去包围，下令说 包围圈一定要留有缺口 。
陕西总督郑崇俭发兵围之，令曰 围师必缺。 
Zheng Chongjian, the Governor-General of Shaanxi, dispatched troops to surround him and ordered that “the encirclement must have an opening”.