Sahih al-Bukhari Book 10, Hadith 76
My father said, "When Allah's Messenger (ﷺ) became seriously ill, he was told about the prayer. He said,
'Tell Abu Bakr to lead the people in the prayer.' `Aisha said, 'Abu Bakr is a softhearted man and he
would be overpowered by his weeping if he recited the Qur'an.' He said to them, 'Tell him (Abu Bakr)
to lead the prayer. The same reply was given to him. He said again, 'Tell him to lead the prayer. You
(women) are the companions of Joseph."
The Prophet (ﷺ) did not come out for three days. The people stood for the prayer and Abu Bakr went ahead to lead the prayer. (In the meantime) the Prophet (ﷺ) caught hold of the curtain and lifted it. When the face of the Prophet (ﷺ) appeared we had never seen a scene more pleasing than the face of the Prophet (ﷺ) as it appeared then. The Prophet (ﷺ) beckoned to Abu Bakr to lead the people in the prayer and then let the curtain fall. We did not see him (again) till he died.
`Aisha said, "Allah's Messenger (ﷺ) ordered Abu Bakr to lead the people in the prayer during his illness and so he led them in prayer." `Urwa, a sub narrator, added, "Allah's Messenger (ﷺ) felt a bit relieved and came out and Abu Bakr was leading the people. When Abu Bakr saw the Prophet (ﷺ) he retreated but the Prophet beckoned him to remain there. Allah's Messenger (ﷺ) sat beside Abu Bakr. Abu Bakr was following the prayer of Allah's Messenger (ﷺ) and the people were following the prayer of Abu Bakr."