Musannaf Ibn Abi Shayba 18:1246

Abu Bakr narrated to us, he said: Ubayd Allah ibn Musa narrated to us, from Ali ibn Salih, from Simak, from Ikrimah, from Ibn Abbas, who said: There were the Qurayza and the Nadir, and the Nadir were more noble than the Qurayza. If a man from the Qurayza killed a man from the Nadir, he was killed for him. But if a man from the Nadir killed a man from the Qurayza, he paid a blood money of one hundred wasqs of dates. When the Prophet, peace and blessings of Allah be upon him, was sent, a man from the Nadir killed a man from the Qurayza. They (the Qurayza) said: "Hand him over to us so we may kill him." They (the Nadir) said: "Between us and you is the Prophet, peace and blessings of Allah be upon him." So they came to him, and there was revealed: "And if you judge, judge between them with justice" (5:42). The justice was a soul for a soul. Then was revealed: "Do they then seek the judgment of the time of ignorance?" (5:50).