Musannaf Ibn Abi Shayba 19:92

Abu Bakr narrated to us, he said: 'Abdah bin Sulayman narrated to us, from Sa'id, from Abu Ma'shar, from Ibrahim, who said regarding a slave girl who is married and [the husband] consummates the marriage with her, then she commits an indecent act: He said: There is no prescribed punishment (*hadd*) upon her until she menstruates.