Sahih al-Bukhari 2232
Sahih al-Bukhari · Book 34: Sales and Trade · The sale id a slave who is promised to be manumitted
Narrated Zaid bin Khalid and Abu Huraira:
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ ، حَدَّثَنَا يَعْقُوبُ ، حَدَّثَنَا أَبِي ، عَنْ صَالِحٍ ، قَالَ حَدَّثَ ابْنُ شِهَابٍ ، أَنَّ عُبَيْدَ اللَّهِ ، أَخْبَرَهُ أَنَّ زَيْدَ بْنَ خَالِدٍ وَأَبَا هُرَيْرَةَ رضى الله عنهما أَخْبَرَاهُ أَنَّهُمَا، سَمِعَا رَسُولَ اللَّهِ صلى الله عليه وسلم يُسْأَلُ عَنِ الأَمَةِ تَزْنِي وَلَمْ تُحْصَنْ قَالَ " اجْلِدُوهَا، ثُمَّ إِنْ زَنَتْ فَاجْلِدُوهَا، ثُمَّ بِيعُوهَا بَعْدَ الثَّالِثَةِ أَوِ الرَّابِعَةِ " .
that Allah's Messenger (ﷺ) was asked about an unmarried slave-girl who committed illegal sexual intercourse. They heard him saying, "Flog her, and if she commits illegal sexual intercourse after that, flog her again, and on the third (or the fourth) offense, sell her."