Musannaf Ibn Abi Shayba 19:217

Abu Bakr narrated to us, he said: Abu Khalid narrated to us, from al-A’mash, from Habib, from Abu Salih, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If the servant of one of you commits adultery, let him flog her. If she repeats it, let him flog her. If she repeats it, let him sell her, even if it be for a rope of hair."