It was narrated that ‘Aishah said:
“The Messenger of Allah (peace be upon him) told Abu Bakr to lead the people in prayer when he was sick, and Abu Bakr used to lead them in prayer. Then the Messenger of Allah (peace be upon him) began to feel a little better, so he came out, and saw Abu Bakr leading the people in prayer. When Abu Bakr saw him, he stepped back, but the Messenger of Allah (peace be upon him) gestured to him to stay where he was. Then the Messenger of Allah (peace be upon him) sat beside Abu Bakr. Abu Bakr was following the prayer of the Messenger of Allah (peace be upon him), and the people were following the prayer of Abu Bakr.”
Sunan Ibn Majah, Book 5, Hadith 1291