It was narrated from al-"Abbas bin "Abdul-Muttalib that the Messenger of Allah (ﷺ) said when he was sick:

"Tell Abu Bakr to lead the people in prayer. So Abu Bakr went out and said takbeer. The Prophet (ﷺ) felt a little better, so he came out, supported by two men. When Abu Bakr saw him, he stepped backwards, but the Prophet (ﷺ) gestured to him: Stay where you are. Then the Messenger of Allah (ﷺ) sat beside Abu Bakr, and carried on the recitation from where Abu Bakr (رضي الله عنه) had reached.