Sahih Muslim 973b

In the pre-Islamic era of ignorance, they used to impose taxes upon the slave girls, which they earned from practicing immorality, then they would attribute the child to the man who committed adultery with the slave girl if he claimed him. So ‘Utbah ibn Abi Waqqās had unlawful sexual intercourse with a slave girl belonging to Zam‘ah ibn al-Aswad, and he entrusted his brother Sa‘d to attribute the child to his lineage (‘Utbah's lineage).

After the Conquest of Makkah, Sa‘d saw the boy and recognized him by his resemblance to his brother. So, he wanted to attribute him to his brother's lineage. On that, Sa‘d and ‘Abd ibn Zam‘ah disputed over the boy. Sa‘d supported his claim by the fact that his brother admitted that the boy was his child, and that there was a resemblance between them.

Whereas ‘Abd ibn Zam‘ah said that he was his brother, born from the slave girl of his father, for his father was the master of the slave girl who gave birth to the boy, therefore he is the legitimate owner of the bed. Thereupon, the Prophet (may Allah's peace and blessings be upon him) looked at the boy and saw in him a clear resemblance to ‘Utbah.

Yet, he ruled that the child belonged to Zam‘ah; saying that the child belongs to the owner of the bed in which he was born, and that the one who commits unlawful sexual intercourse gets nothing but failure and loss, for he has no link with the child. That is because, in principle, the child is to be attributed to the slave girl's owner who is entitled to have sexual intercourse with rightfully.

However, when he saw the boys resemblance to ‘Utbah, he was cautious to let the boy look freely at his sister Sawdah bint Zam‘ah, on the basis that they were siblings. So, he ordered her to cover hereself from him as a precautionary measure. Hence, resemblance and supplementary proofs are not considered valid in the presence of owner of the bed.