We sold slave-mothers during the time of the Messenger of Allah ﷺ and of AbuBakr. When Umar was in power, he forbade us and we stopped. (Using translation from Abū Dāʾūd 3954)
«بِعْنَا أُمَّهَاتِ الْأَوْلَادِ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ وَأَبِي بَكْرٍ فَلَمَّا كَانَ عُمَرُ نَهَانَا فَانْتَهَيْنَا»