《三国志·魏书·诸夏侯曹传》
况且壶关城墙坚固，储粮丰富，攻打他们，会造成士兵伤亡，如果只是包围，又要耗费大量时间；现在在坚固的城池下驻军，攻打必死的敌人，这不是好计策。 
且城固而粮多，攻之则士卒伤，守之则引日久；今顿兵坚城之下，以攻必死之虏，非良计也。 
Moreover, Huguan's city walls are strong and there is plenty of food. Attacking them will cause casualties among the soldiers. If we just besiege them, it will take a lot of time. Now that we are stationed under the strong city and attacking the enemy who is bound to die, this is not a good strategy.