Musnad Abu Ya'la al-Mawsili 111:37

Ishaq ibn Abi Isra'il narrated to us, Hisham ibn Yusuf narrated to us, al-Qasim, the nephew of Khallad ibn 'Abd al-Rahman, narrated to me, from Khallad ibn 'Abd al-Rahman, from Sa'id ibn al-Musayyib, that he heard Ibn 'Abbas saying: While the Messenger of Allah (may Allah bless him and grant him peace) was delivering the sermon to the people on Friday, a man from the tribe of Banu Layth ibn Bakr ibn 'Abd Manat ibn Kinana came to him, stepping over the people until he drew near to him. He said, "O Messenger of Allah, execute the prescribed punishment (hadd) upon me." The Prophet (may Allah bless him and grant him peace) said to him, "Sit down." So he sat down. Then he stood up a second time, and he said, "Sit down." Then he stood up a third time and said the same thing. Then he said, "And what is your prescribed punishment?" He said, "I came to a woman unlawfully." The Prophet (may Allah bless him and grant him peace) said to some of his companions, among whom were 'Ali ibn Abi Talib, al-'Abbas, Zayd ibn Harithah, and 'Uthman ibn 'Affan, "Go with him and flog him one hundred lashes." The Laythi man had not been married. It was said, "O Messenger of Allah, will you not flog the one with whom he committed the indecency?" The Prophet (may Allah bless him and grant him peace) said, "Bring him to me after he has been flogged." When he was brought to him, the Prophet (may Allah bless him and grant him peace) said, "Who was your companion?" He said, "So-and-so, a woman from the tribe of Banu Bakr." He summoned her and asked her about that. She said, "By Allah, he lies. I do not know him, and I am innocent of what he said. Allah is a witness to what I say." The Prophet (may Allah bless him and grant him peace) said, "Who witnessed that you committed indecency with her? For she denies it. If you have witnesses, I will flog her with the prescribed punishment; otherwise, I will flog you with the punishment for false accusation (qadhf)." He said, "O Messenger of Allah, I have no witnesses." So he ordered him to be flogged with the punishment for false accusation, eighty lashes.