In the Holy Qur'an

Take to forgiveness and enjoin good and turn aside from the ignorant (7:199)

In the Traditions

When a man asked the Prophet to explain nobility of character to him, he replied. "It means that you should forgive him who has wronged you, re-establish ties with him who has broken them off, give to him who has denied you something, and tell the truth even if it is against your own interests."

Imam Ali said, "If you overcome your enemy, then make your forgiveness of them gratitude for your position of strength over them"