النحل — An-Nahl Ayat 126
وَاِنْ عَاقَبْتُمْ فَعَاقِبُوْا بِمِثْلِ مَا عُوْقِبْتُمْ بِهٖۗ وَلَىِٕنْ صَبَرْتُمْ لَهُوَ خَيْرٌ لِّلصّٰبِرِيْنَ
Wa in ‘āqabtum fa ‘āqibū bimiṡli mā ‘ūqibtum bih(ī), wa la'in ṣabartum lahuwa khairul liṣ-ṣābirīn(a).
"And if you punish [an enemy, O believers], punish with an equivalent of that with which you were harmed. But if you are patient - it is better for those who are patient."