Musannaf Ibn Abi Shaybah

Hazrat Ibn Sirin says that when a person buys a slave woman, he should not go near her until he is certain that she is free from pregnancy.

Hasan says that if a person buys a slave woman, he should make sure that her womb is empty.

Hasan says that be certain of the slave girl's being free from pregnancy, even if she is a virgin.

The same is narrated from Hazrat Ikrimah.

Hazrat Ata says that whoever buys a slave-girl should make sure of her being free from pregnancy by waiting for two menstrual periods, and if she does not menstruate, then he should wait for forty-five days.

Hazrat Ibn Umar (may Allah be pleased with them both) narrates that whoever buys a veiled slave-girl, it is not necessary to ascertain that she is free from pregnancy.