Maliks Muwatta Book 38, Hadith Number 6.

Section : Freeing Slaves who are Umm Walad and a General Chapter on Freeing.

Malik related to me from Nafi from Abdullah ibn Umar that Umar ibn al-Khattab said, “If a slave-girl gives birth to a child by her master, he must not sell her, give her away, or bequeath her. He enjoys her and when he dies she is free.”