Musnad Abu Ya'la al-Mawsili 150:44

Muhammad ibn 'Abbad narrated to us, Sufyan narrated to us, he said: I memorized from al-Zuhri, from 'Urwah, from 'Aishah, who said: The Messenger of Allah (ﷺ) used to come to us every day at the two ends of the day. Then he came to us one day in the middle of the afternoon and said: "O Abu Bakr, is there anyone present?" He said: "O Messenger of Allah, it is only Umm Ruman, Asma', and 'Aishah." He said: "For my Lord, Blessed and Exalted is He, has given me permission to depart." He said: "The companionship, O Messenger of Allah?" He said: "The companionship." Abu Bakr had already prepared two riding camels, so he said: "O Messenger of Allah, take one of my two riding camels and ride it." He said: "No, rather for the price, O Abu Bakr."