An-Nahl - 16:126

وَإِنْ عَاقَبْتُمْ فَعَاقِبُواْ بِمِثْلِ مَا عُوقِبْتُم بِهِ وَلَئِن صَبَرْتُمْ لَهُوَ خَيْرٌ لِّلصَّابِرينَ
[16:126]
And if you take your turn, then retaliate with the like of that with which you were afflicted; but if you are patient, it will certainly be best for those who are patient.
And if ye do catch them out, catch them out no worse than they catch you out: But if ye show patience, that is indeed the best (course) for those who are patient.
If ye punish, then punish with the like of that wherewith ye were afflicted. But if ye endure patiently, verily it is better for the patient.