《后汉书·列传·刘虞公孙瓚陶谦列传》
坚守日子长了，或许可以让袁绍自己退兵；如丢下逭裹冲出去，身后没有威重人物的镇守，易京的危亡，立等可到啊。 
坚守旷日，或可使绍自退。若舍之而出，后无镇重，易京之危，可立而待也。 
If the siege lasts for a long time, Yuan Shao may withdraw his troops on his own. If the battalion is abandoned and the troops rush out, there will be no important figures in charge after the troops leave, and the danger of Yijing will come immediately.