It is narrated from Sayyiduna Abu Shurayh al-Khuza'i (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever is afflicted by a killing or a wound has the choice of one of three things: either he takes retaliation, or he forgives, or he takes the blood money. If he has taken the blood money, then seize his hand (to restrain him); and if he transgresses after that, for him is the Fire of Hell."
Hadith Referenceالمعجم الكبير للطبراني / باب الهاء / 18714