Musnad Ahmad 32:1087

Ya'qub narrated to us, my father narrated to us, from Salih ibn Kaysan, who said: Ibn Shihab said: Anas ibn Malik informed me that Abu Bakr used to lead them in prayer during the illness of the Messenger of Allah, peace and blessings of Allah be upon him, in which he passed away. Until it was Monday, and they were in rows for the prayer, he said: The Messenger of Allah, peace and blessings of Allah be upon him, drew back the curtain of the chamber, and he mentioned the rest of its meaning.