Musannaf Ibn Abi Shayba 3:4786

Husayn ibn Ali narrated to us, from Za'idah, from Abd al-Malik ibn Umayr, from Abu Burdah, from Abu Musa, who said: The Messenger of Allah (may Allah bless him and grant him peace) became ill, and his illness intensified. He said, "Command Abu Bakr to lead the people in prayer." Aisha said, "O Messenger of Allah, Abu Bakr is a soft-hearted man; whenever he stands in your place, he will not be able to lead the people in prayer." He said, "Command Abu Bakr to lead the people in prayer, for you are the companions of Yusuf." He said: So Abu Bakr led them in prayer during the lifetime of the Messenger of Allah (may Allah bless him and grant him peace).