Musannaf Ibn Abi Shaybah 24811 — A man who sold his umm walad

It is narrated from Hammad that if a man sells his umm walad (a slave woman who has borne him a child), then the buyer also has intercourse with her and she bears another child to this second man, what is the ruling? He answered that this slave woman is to be returned to the first man. The slave woman is to receive the dower of her peers, and her second child will likewise count as a slave like her and will become free when the mother is freed. The second man will recover from the first the price he paid for the slave woman. Then, if one of them knew that this was not permissible, he is to be punished, and if both knew, both deserve punishment.