Musnad Ahmad 27:1955

'Abd al-Samad narrated to us, Hammam narrated to us, Nafi' narrated to us, from Ibn 'Umar, that 'Aishah bargained for Barirah. The Prophet, peace and blessings of Allah be upon him, returned from the prayer, and she said: "They refused to sell her unless they stipulated the right of inheritance (al-wala')." The Prophet, peace and blessings of Allah be upon him, said: "The right of inheritance (al-wala') belongs to the one who emancipated."