Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: On the day of the Conquest of Makkah, a man of Banu Khuza'ah killed a man of Banu Layth in retaliation for something they had done in the Jahiliyyah. Then he narrated the complete previous hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 16040