أُذِنَ لِلَّذينَ يُقاتَلونَ بِأَنَّهُم ظُلِموا وَإِنَّ اللَّهَ عَلىٰ نَصرِهِم لَقَديرٌ (39)

Permission [to fight] has been given to those who are being fought, because they were wronged. And indeed, Allah is competent to give them victory.