Musannaf Ibn Abi Shayba 13:2288

Abu Bakr narrated to us, he said: Hushaym narrated to us, from Abu Salih al-Fazari, from ‘Abayah ibn Rifa‘ah ibn Rafi‘ al-Ansari, that his grandfather died and left behind a slave woman who was a *nafl* (a gift or booty). This was mentioned to the Prophet, peace and blessings of Allah be upon him, and he disliked the earnings of the slave woman. He said: "Perhaps she will not find [work], so she will commit adultery with herself."