Musannaf Ibn Abi Shayba 3:4784

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from Ibrahim, from Al-Aswad, from ‘Aisha, who said: When the Messenger of Allah (may Allah bless him and grant him peace) fell ill with the illness in which he died, Bilal came to inform him of the prayer. He said: "Command Abu Bakr to lead the people in prayer." We said: "O Messenger of Allah, Abu Bakr is a tender-hearted, soft-natured man, and whenever he stands in your place, he will weep and will not be able to [recite]. If only you would command ‘Umar." He said: "Command Abu Bakr to lead the people in prayer, for you are [like] the companions of Yusuf." So he sent for Abu Bakr, and he led the people in prayer. Then the Prophet (may Allah bless him and grant him peace) felt a lightness in himself, so he went out to the prayer, supported between two men, with his feet dragging on the ground. When Abu Bakr sensed him, he went to step back, but the Prophet (may Allah bless him and grant him peace) gestured to him to stay in his place. She said: The Prophet (may Allah bless him and grant him peace) came and sat beside Abu Bakr. Abu Bakr would follow the Prophet (may Allah bless him and grant him peace) in prayer, and the people would follow Abu Bakr.