Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Hammad that if a man sells his umm walad (a slave woman who has borne him a child), and then the buyer also has intercourse with her, and that slave woman gives birth to another child while with the second man, then what is the ruling? He replied that this slave woman will be returned to the first person. The slave woman will receive a mahr mithl (customary dower), and her second child will also be considered a slave like her, and upon the emancipation of the property, he too will be 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 will be punished, and if both knew, then both are deserving of punishment.