Sahih Muslim Book 17, Hadith Number 4219.

Chapter : Stoning to death of jews and other Dhimmis in case of adultery.

Abu Huraira reported that he heard Allah’s Messenger (may peace be upon him) as saying: When the slave-woman of any of you commits adultery and this (offence of hers) becomes clear, she should be flogged (as the prescribed) punishment, but hurl no reproach at her. If she commits adultery again, she should (again be punished) by flogging, but hurl no reproach upon her. It she commits fornication for the third time and it becomes clear, then he should sell her, even if only for a rope of hair.