There was a fight between members of Banu Amr bin Awf, and news of it reached the Prophet ﷺ. He prayed Zuhr and then went out to make peace between them.He said to Bilal, "Bilal, if the time for Asr comes and I have not returned, instruct Abu Bakr to lead the people in prayer."When the time came, Bilal made the call to prayer and then the iqamah, and said to Abu Bakr , "Step forward."So Abu Bakr stepped forward and began the prayer. Then the Messenger of Allah ﷺ arrived and started making his way through the people until he stood behind Abu Bakr. The people began clapping. Now, when Abu Bakr entered the prayer, he would not turn around, but when he noticed that the clapping would not stop, he turned and saw the Messenger of Allah ﷺ gesturing to him with his hand. He praised Allah
for what the Messenger of Allah ﷺ had indicated to him, telling him to continue.Then Abu Bakr stepped backward on his heels and withdrew. When the Messenger of Allah ﷺ saw this, he stepped forward and led the people in prayer.When he finished his prayer, he said, "Abu Bakr, what prevented you from continuing when I gestured to you?"Abu Bakr replied, "It is not for the son of Abu Quhafa to lead the Messenger of Allah ﷺ in prayer."Then he said to the people, "If something happens during the prayer, let the men say 'Subhan Allah' and let the women clap."
أخبرنا أحمد بن عبدة عن حماد بن زيد ثم ذكر كلمة معناها قال حدثنا أبو حازم
كان قتال بين بني عمرو بن عوف فبلغ ذلك النبي ﷺ فصلى الظهر ثم أتاهم ليصلح بينهم ثم قال لبلال يا بلال إذا حضر العصر ولم آت فمر أبا بكر فليصل بالناس فلما حضرت أذن بلال ثم أقام فقال لأبي بكر رضي الله عنه تقدم فتقدم أبو بكر فدخل في الصلاة ثم جاء رسول الله ﷺ فجعل يشق الناس حتى قام خلف أبي بكر وصفح القوم وكان أبو بكر إذا دخل في الصلاة لم يلتفت فلما رأى أبو بكر التصفيح لا يمسك عنه التفت فأومأ إليه رسول الله ﷺ بيده فحمد الله عز وجل على قول رسول الله ﷺ له امضه ثم مشى أبو بكر القهقرى على عقبيه فتأخر فلما رأى ذلك رسول الله ﷺ تقدم فصلى بالناس فلما قضى صلاته قال يا أبا بكر ما منعك إذ أومأت إليك أن لا تكون مضيت فقال لم يكن لابن أبي قحافة أن يؤم رسول الله ﷺ وقال للناس إذا نابكم شيء فليسبح الرجال وليصفح النساء
Bukhari narrated it in the Book of Judgments, chapter "The Imam Who Comes to a People to Reconcile Between Them," hadith no. 7190, from the hadith of Hammad bin Zayd with similar meaning, and it is also in Kubra, hadith no. 868.