The Prophet ﷺ was asked about a slave woman who commits fornication and is not married. He said, "Flog her. If she commits it again, flog her." Then on the third or fourth occurrence he said, "If she commits it again, sell her, even for a plaited rope." The plaited rope means a cord. The uncertainty over whether it was the third or the fourth occurrence comes from Zuhri.
حدثنا عبد الرزاق حدثنا معمر عن الزهري عن عبيد الله بن عبد الله بن عتبة عن زيد بن خالد الجهني وأبي هريرة قالا سئل النبي ﷺ عن الأمة فذكر الحديث وقال في الثالثة أو الرابعة الزهري شك