Musannaf Ibn Abi Shayba 13:608

Abu Bakr narrated to us, he said: Hafs ibn Ghiyath narrated to us, from ‘Amr ibn Maymun, from Sulayman ibn Yasar, who said: I sought permission to enter upon ‘Aisha. She said, "Sulayman?" I said, "Sulayman." She said, "Have you fulfilled what remains upon you of your *kitabah* (contract of manumission)?" And I had made a contract with her. He said: I said, "Yes, except for a small amount." She said, "Enter, for you are a slave as long as anything remains upon you."