Musannaf Ibn Abi Shayba 19:448

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Isma’il bin Abi Khalid, from ‘Umayr bin Numayr, who said: Ibn ‘Umar was asked about a slave girl who was between two men, and one of them had intercourse with her. He said: There is no prescribed punishment (*hadd*) upon him; he is a traitor. He shall be appraised for her value, and he shall take her.