Musannaf Ibn Abi Shayba 18:906

Abu Bakr narrated to us, he said: Muhammad ibn Bakr narrated to us, from Ibn Jurayj, he said: Al-Hasan ibn Muslim informed me that a slave woman bit the finger of a client of the Banu Zayd, and it became gangrenous, and he died. The slave woman confessed to biting him. Umar ibn Abd al-Aziz judged regarding her that the Banu Zayd must swear fifty oaths, the oaths being repeated upon them, that he died from her bite, and then the slave woman would belong to them; otherwise, they would have no right. They refused to swear.