The Messenger of Allah ﷺ was asked about a slave-woman who commits fornication, and she is not married: If she commits fornication, flog her: if she commits fornication again flog her; if only for a rope of hair (dafir). Ibn Shihab: I do not know whether he (the Prophet) said it is a third or a fourth time. (Using translation from Abū Dāʾūd 4469)

أَنَّ رَسُولَ اللَّهِ ﷺ سُئِلَ عَنِ الْأَمَةِ إِذَا زَنَتْ وَلَمْ تُحْصَنْ فَقَالَ «إِذَا زَنَتْ فَاجْلِدُوهَا ثُمَّ إِنْ زَنَتْ فَاجْلِدُوهَا ثُمَّ إِنْ زَنَتْ فَاجْلِدُوهَا ثُمَّ بِيعُوهَا وَلَوْ بِضَفِيرٍ»