Sahih Bukhari Volume 3, Book 34, Hadith 2154

حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِي هُرَيْرَةَ، وَزَيْدِ بْنِ خَالِدٍ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم سُئِلَ عَنِ الأَمَةِ إِذَا زَنَتْ وَلَمْ تُحْصِنْ قَالَ ‏"‏ إِنْ زَنَتْ فَاجْلِدُوهَا، ثُمَّ إِنْ زَنَتْ فَاجْلِدُوهَا، ثُمَّ إِنْ زَنَتْ فَبِيعُوهَا وَلَوْ بِضَفِيرٍ ‏"‏‏.‏ قَالَ ابْنُ شِهَابٍ لاَ أَدْرِي بَعْدَ الثَّالِثَةِ، أَوِ الرَّابِعَةِ‏.‏

Narrated By Abu Huraira and Zaid bin Khalid : Allah's Apostle was asked about the slave-girl, if she was a virgin and committed illegal sexual intercourse. The Prophet said, "If she committed illegal sexual intercourse, lash her, and if she did it a second time, then lash her again, and if she repeated the third time, then sell her even for a hair rope." Ibn Shihab said, "I don't know whether to sell her after the third or fourth offence."