Musnad Ahmad 1153:1266

Mu'awiyah ibn Hisham narrated to us, he said: Sufyan narrated to us, from Rabi'ah, from al-Qasim, from 'Aishah, she said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The right of inheritance (al-wala') belongs to the one who emancipated."