Allah سبحانه وتعالى says in the Holy Qurān,
وَلَا تَسْتَوِي الْحَسَنَةُ وَلَا السَّيِّئَةُ ادْفَعْ بِالَّتِي
هِيَ أَحْسَنُ فَإِذَا الَّذِي بَيْنَكَ وَبَيْنَهُ عَدَاوَةٌ
كَأَنَّهُ وَلِيٌّ حَمِيمٌ
Nor can good and evil be equal. Repel thou evil with that which is goodly then behold he between whom and thee there was enmity, will be as though he was a warm friend.
[al Fussilat 41/34]
The teaching of Islam is that no matter how others treat us, we should always respond with that which is better. If we merely adopt the principle of ‘an eye for an eye’ i.e. good for good and evil for evil, then metaphorically speaking, there will no one left with an eye; someone has to give way. In Islam we are required to show the initiative in doing good and not just reciprocate good. By persevering upon this conduct, even an enemy will become a close friend.
[This short excerpt is based on a majlis (gathering held for spiritual training) held by Shaykh Riyadh ul Haq on 31st March 2004].