Sahl bin Sa'd said:
There was some fighting among Banu 'Amr bin 'Awf, and news of that reached the Prophet (ﷺ). He prayed Zuhr, then he went to them to reconcile between them. Then he said to Bilal: 'O Bilal, if the time for Asr comes and I have not come back, then tell Abu Bakr to lead the people in prayer.' When the time (for Asr) came, Bilal called the Adhan, then the Iqamah, then he said to Abu Bakr: 'Go forward. So Abu Bakr went forward and started to pray. Then the Messenger of Allah (ﷺ) came and started passing through the rows of people until he stood behind Abu Bakr, and the people clapped. Abu Bakr was such that whenever he started praying, he would never glance sideways, but when he noticed that the clapping persisted he turned around. The Messenger of Allah (ﷺ) gestured to him to carry on praying. Abu Bakr praised Allah the Mighty and Sublime for the Messenger of Allah (ﷺ) having told him to continue. Then Abu Bakr moved backward on his heels, and when the Messenger of Allah (ﷺ) saw that, he came forward and led the people in prayer. When he completed the prayer he said: 'O Abu Bakr, when I gestured to you, what kept you from continuing (to lead the people)?' He said: 'It does not befit the son of Abu Quhafah to lead the Messenger of Allah (ﷺ) in prayer.' And he (the Prophet) said to the people: 'If you notice something (during the prayer), men should say Subhan Allah and women should clap.'