SHAFAQNA – In one of the wars, a strong enemy fighter asked to fight a person from Bani Hashim but he declined. Imam Ali (AS) asked him: Why you have refused to fight? He replied: This enemy is very strong, I am worried he will defeat me. Imam Ali (AS) said: Because that person is in enemy’s army, he is an oppressor and if you fight him, you will win; know that, if a mountain oppresses another one, the oppressor will be defeated and destroyed .
 Wasa’elul Shia, Vol. 11, Page 334.