《三国志·蜀书·蒋琬费祎姜维传》
魏朝遣大将军曹爽攻打蜀国时，商议的人有人认为，只可以守城，不应该出城抗敌，敌军一定会自动退回。
魏遣大将军曹爽袭蜀时，议者或谓但可守城，不出拒敌，必自引退。
When Cao Shuang, the Great General of Wei, plotted to attack Shu, some suggested that they should only stay within the city walls and not go out to fight. The enemy army would surely retreat on its own.