Musnad Abu Ya'la al-Mawsili 150:70

Muhammad ibn Abdullah ibn Numayr narrated to us, Khallad narrated to us, from Ubaydullah ibn Sa'id Abu Muslim, from al-A'mash, from Abu al-Duha, from Masruq, from Aisha, she said: The Messenger of Allah (may Allah bless him and grant him peace) entered upon me. I feared that I might have been commanded regarding something, so he gave me a choice. I said: "Have you mentioned this to anyone before me?" He said: "No." I said: "Indeed, I have chosen you." And he gave all of his wives a choice, and they chose him, and he did not consider it anything.