Sahih Muslim
The Book of Divorce (Kitab Al-Talaq)
Book Number: 009 / Hadith Number: 3584
Ibn Umar reported that 'A'isha decided to buy a slave-girl and then set her free, but her masters said: We are prepared to sell her to you on the condition that her right of inheritance would vest with you. She (Hadrat A'isha) made a mention of that to Allah's Messenger (may peace be upon him) whereupon he said: This should not stand in your way. The right of inheritance vests in one who emancipates.