Hammad bin Usamah حماد بن أسامة - أبو أسامة · The Chapters on Manumission (of Slaves)

“We used to sell our slave women and the mothers of our children (Umahat Awaldina) when the Prophet (ﷺ) was still living among us, and we did not see anything wrong with that.”

“Umm Salamah freed me but stipulated that I should serve the Prophet (ﷺ) as long he lived.”