《左传·宣公·宣公十七年》
让回去的人有了逃走的理由，而伤害前来的人，以使诸侯害怕，这有什么用？ 
使反者得辞，而害来者，以惧诸侯，将焉用之？ 
We let the person who went back find a reason to escape and hurt the ones who came. This was to make the vassal states afraid. What's the use of that?