Musannaf Ibn Abi Shayba 9:1273

Waki’ narrated to us, from Musa ibn ‘Ubaydah, from Muhammad ibn Ka’b, ‘Uthman ibn al-Hakam, and ‘Abdullah ibn ‘Utbah, they said: The one who gifted herself to the Prophet, may Allah bless him and grant him peace, was Maymunah.