(21) باب اسْتِخْلاَفِ الإِمَامِ إِذَا عَرَضَ لَهُ عُذْرٌ مِنْ مَرَضٍ وَسَفَرٍ وَغَيْرِهِمَا مَنْ يُصَلِّي بِالنَّاسِ وَأَنَّ مَنْ صَلَّى خَلْفَ إِمَامٍ جَالِسٍ لِعَجْزِهِ عَنِ الْقِيَامِ لَزِمَهُ الْقِيَامُ إِذَا قَدَرَ عَلَيْهِ وَنَسْخِ الْقُعُودِ خَلْفَ الْقَاعِدِ فِي حَقِّ مَنْ قَدَرَ عَلَى الْقِيَامِ
A'mash reported:
When the Messenger of Allah (ﷺ) suffered from illness of which he died, and in the hadith transmitted by Ibn Mus-hir, the words are: The Messenger of Allah (ﷺ) was brought till he was seated by his (Abu Bakr's) side and the Apostle (ﷺ) led the people in prayer and Abu Bakr was making takbir audible to them, and in the hadith transmitted by 'Isa the (words are):" The Messenger of Allah (ﷺ) sat and led the people in prayer and Abu Bakr was by his side and he was making (takbir) audible to the people."
Reference: Sahih Muslim 418 g
In-book reference: Book 4, Hadith 104
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 838