Musnad Ahmad 950:1

Ya'la ibn 'Ubayd narrated to us, Muhammad—meaning Ibn Ishaq—narrated to us, from Ya'qub ibn 'Abd Allah ibn al-Ashajj, from Abu Umamah ibn Sahl, from Sa'id ibn Sa'd ibn 'Ubadah, who said: There was among our houses a man who was maimed and weak. The people of the house were not aware until he was upon a slave-girl from among the slave-girls of the house, committing indecency with her, and he was a Muslim. Sa'd brought his case before the Messenger of Allah, peace and blessings of Allah be upon him, who said: "Strike him with his prescribed punishment." They said: "O Messenger of Allah, he is weaker than that; if we strike him one hundred [times], we will kill him." He said: "Then take a palm branch containing one hundred thin stalks, and strike him with it one single strike, then let him go."