Jabir (may Allah be pleased with him) narrated that a man struck another man in the knee with a horn. That man came to the Prophet (peace and blessings be upon him) for retaliation, and he (peace and blessings be upon him) said: "Get well, then come." He refused and immediately demanded retaliation. Retaliation was given to him, and the knee of the one from whom retaliation was taken healed, while his did not. So he (peace and blessings be upon him) said: "There is nothing for you; this is because of your refusal."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 16107