Holy Quran, Chapter 22 Verse 60
ذَلِكَ وَمَنْ عَاقَبَ بِمِثْلِ مَا عُوقِبَ بِهِ ثُمَّ بُغِيَ عَلَيْهِ لَيَنصُرَنَّهُ اللَّهُ إِنَّ اللَّهَ لَعَفُوٌّ غَفُورٌ
“That (is so); and he who retaliated with the like of that whereby he was wronged, and again he was wronged, then most certainly Allah will help him; verily Allah is merciful, oft- forgiving” (more…)