Musannaf Ibn Abi Shayba 13:3226

Abu Bakr narrated to us, he said: Zayd ibn al-Hubab narrated to us, he said: Husayn ibn Waqid informed me, he said: Uthman Abu al-Manazil, the nephew of Shurayh, narrated to me, from Shurayh, that he used to not permit the testimony of the owner of a bathhouse, nor the owner of the bathhouse.