Sayyiduna Abu Shurayh al-Khuza'i (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever has someone of his killed or wounded may choose whichever he wishes of three things; if he does a fourth thing, then hold back his hands. Those three things are: 1. he takes retaliation, 2. he receives blood money, 3. he forgives. If, after accepting any of these, he then transgresses, he is of the people of Hell."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 16038