The Book of Prayers
4/21. Chapter:
If The Imam Experiences An Excuse, From Illness, Or Travelling, Etc. He May Appoint Someone Else To Lead The People In Prayer; The One Who Offers Prayer Behind The Imam Sitting Because He Is Unable To Stand Must Stand If He Is Able To Do So; And The Abrogation Of Sitting Behind A Sitting Imam For Those Who Are Able To Stand
Sahih Muslim
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا ابْنُ نُمَيْرٍ، عَنْ هِشَامٍ، ح وَحَدَّثَنَا ابْنُ نُمَيْرٍ، - وَأَلْفَاظُهُمْ مُتَقَارِبَةٌ - قَالَ حَدَّثَنَا أَبِي قَالَ، حَدَّثَنَا هِشَامٌ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ أَمَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَبَا بَكْرٍ أَنْ يُصَلِّيَ بِالنَّاسِ فِي مَرَضِهِ فَكَانَ يُصَلِّي بِهِمْ . قَالَ عُرْوَةُ فَوَجَدَ رَسُولُ اللَّهِ صلى الله عليه وسلم مِنْ نَفْسِهِ خِفَّةً فَخَرَجَ وَإِذَا أَبُو بَكْرٍ يَؤُمُّ النَّاسَ فَلَمَّا رَآهُ أَبُو بَكْرٍ اسْتَأْخَرَ فَأَشَارَ إِلَيْهِ رَسُولُ اللَّهِ صلى الله عليه وسلم أَىْ كَمَا أَنْتَ فَجَلَسَ رَسُولُ اللَّهِ حِذَاءَ أَبِي بَكْرٍ إِلَى جَنْبِهِ . فَكَانَ أَبُو بَكْرٍ يُصَلِّي بِصَلاَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَالنَّاسُ يُصَلُّونَ بِصَلاَةِ أَبِي بَكْرٍ .
`A'isha reported: The Messenger of Allah (ﷺ) ordered Abu Bakr that he should lead people in prayer during his illness, and he led them in prayer. `Urwa said: The Messenger of Allah (ﷺ) felt relief and went (to the mosque) and Abu Bakr was leading the people in prayer. When Abu Bakr saw him he began to withdraw, but the Messenger of Allah (ﷺ) signaled him to remain where he was. The Messenger of Allah (ﷺ) sat opposite to Abu Bakr by his side. Abu Bakr said prayer following the prayer of the Messenger of Allah (ﷺ), and the people said prayer following the prayer of Abu Bakr.
Reference : Sahih Muslim 418hIn-book reference : Book 4, Hadith 105USC-MSA web (English) reference : Book 4, Hadith 839