Musannaf Ibn Abi Shaybah

Hazrat Nafi' narrates that Safiyyah bint Abi Ubaid had a slave. She married him to one of her virgin slave girls. That slave girl did not like her husband and wanted to be freed. Safiyyah bint Abi Ubaid feared that if she freed the slave girl, she would separate from her husband. So, she first freed the male slave and then later freed the slave girl.