Musannaf Ibn Abi Shayba 18:1281

Abu Bakr narrated to us, he said: Abu Abd al-Rahman al-Mas'udi narrated to us, from Abdullah ibn Abd al-Malik ibn Abi Ubaydah, from Najiyah Abu al-Hasan, from his father, that Ali was brought a man who had slapped another man. He said to the one who was slapped: "Take retribution."