Maliks Muwatta Book 40, Hadith Number 5.

Section : A Master’s Intercourse with His Slave-girl when he has Made her Mudabbara.

Malik related to me from Yahya ibn Said that Said ibn al-Musayyab used to say, “When a man makes his slave-girl mudabbara, he can have intercourse with her. He cannot sell her or give her away and her children are in the same position as her.”