We used to sell mothers of children during the lifetime of the Messenger of Allah ﷺ.
حدثنا محمد بن جعفر حدثنا شعبة عن زيد أبي الحواري قال سمعت أبا الصديق يحدث
كنا نبيع أمهات الأولاد على عهد رسول الله ﷺ
Its isnad is hasan, because of Zayd bin Hawari, who has slight weakness as we said. The hadith is sahih, reported by Hakim 2/19 through several routes, and Dhahabi agreed with him on many of them. Because of its weakness, many jurists did not act upon it and prohibited the sale of the mother of a child (umm al-walad).