Surah Al-Hajj Verse 39

أُذِنَ لِلَّذِينَ يُقَاتَلُونَ بِأَنَّهُمْ ظُلِمُوا ۚ وَإِنَّ اللَّهَ عَلَىٰ نَصْرِهِمْ لَقَدِيرٌ

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