《北齐书·列传·卷十一》
芒山的胜利，后主对高长恭说： 进入敌阵太深，失利后悔就来不及了。 
邙山之捷，后主谓长恭曰： 入阵太深，失利悔无所及。 
After the victory at Mang Mountain, Emperor Hou said to Gao Changgong, 'If you advance too deep into the enemy's battle formation, if you lose, it will be too late to regret it.'