Musnad Ahmad 3:18

Bahz narrated to us, Mahdi ibn Maymun informed us, Muhammad ibn Abdullah ibn Abi Ya'qub narrated to us, from al-Hasan ibn Sa'd, the freed slave of al-Hasan ibn Ali, from Rabah, who said: My family married me to a Roman slave girl of theirs. I had intercourse with her, and she bore me a black boy like myself, so I named him Abdullah. Then I had intercourse with her, and she bore me a black boy like myself, so I named him Ubaydullah. Then a Roman slave of my family, called Yuhannis, became fond of her and spoke to her in his language. He said: She then bore a boy who looked like a gecko among the geckos. I said to her: "What is this?" She said: "He is Yuhannis'." He said: We were brought before the Commander of the Faithful, Uthman, may Allah be pleased with him—Mahdi said: I think he said: He questioned them both and they confessed—so he said: "Are you both satisfied that I judge between you with the judgment of the Messenger of Allah, peace and blessings of Allah be upon him?" He said: "For the Messenger of Allah, peace and blessings of Allah be upon him, judged that the child belongs to the bed, and for the adulterer is the stone." Mahdi said: And I think he said: He flogged her and he flogged him, and they were both slaves.