Musannaf Ibn Abi Shayba 19:212

Abu Bakr narrated to us, he said: Waki’ and Ghundar narrated to us, from Shu’bah, from ‘Amr ibn Murrah, from ‘Abd al-Rahman ibn Abi Layla, he said: I reached the elders of the Ansar, and when a slave woman would commit adultery, they would flog her in their gatherings.