Nafi' narrates from Sayyiduna Ibn Umar (may Allah be pleased with them both) that Sayyidah Aishah (may Allah be pleased with her) intended to buy a slave girl and free her, but her people said: Her wala' will be ours. So Sayyidah Aishah (may Allah be pleased with her) mentioned this to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Let nothing stop you, for the wala' belongs only to the one who frees."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21730