Sa'id bin Muslim al-Madani says: I heard Salim Sablan, the freed slave of the Nasriyyin, mention that he used to hire out (mounts) to Sayyidah Aishah (may Allah be pleased with her), the Mother of the Believers, for Hajj and Umrah. He says: I made a contract of manumission (mukatabah), then I came and stood at the door and sought permission in a way I had not used to seek it. She disapproved of that and said: O my son, why do you not come in? I said: O Mother of the Believers, I have made a contract of manumission. She said: Then come in to me as long as even one dirham remains due from you, for you remain owned (a slave) as long as even one dirham of your contract remains due from you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21646