Sayyidah Maymunah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), said: I freed a slave girl of mine, and the Prophet (peace and blessings be upon him) came to me, so I told him (peace and blessings be upon him) that I had freed her. He (peace and blessings be upon him) said: "May Allah reward you. Had you given her to your maternal relatives, it would have been greater in reward for you."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20427