كتاب الصلاة
4  
The Book of Prayers
(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
(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
Sahih Muslim 418 e

'A'isha reported:

When the Messenger of Allah (ﷺ) came to my house, he said: Ask Abu Bakr to lead people in prayer. 'A'isha narrated: I said, Messenger of Allah, Abu Bakr is a man of tenderly feelings; as he recites the Qur'an, he cannot help shedding tears: so better command anyone else to lead the prayer. By Allah, there is nothing disturbing in it for me but the idea that the people may not takeevil omen with regard to one who is the first to occupy the place of the Messenger of Allah (ﷺ). I tried to dissuade him (the Holy Prophet) twice or thrice (from appointing my father as an Imam in prayer), but he ordered Abu Bakr to lead the people in prayer and said: You women are like those (who had) surrounded Yusuf.
حَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، وَعَبْدُ بْنُ حُمَيْدٍ، - وَاللَّفْظُ لاِبْنِ رَافِعٍ - قَالَ عَبْدٌ أَخْبَرَنَا وَقَالَ ابْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، - أَخْبَرَنَا مَعْمَرٌ، قَالَ الزُّهْرِيُّ وَأَخْبَرَنِي حَمْزَةُ بْنُ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ عَائِشَةَ، قَالَتْ لَمَّا دَخَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْتِي قَالَ ‏"‏ مُرُوا أَبَا بَكْرٍ فَلْيُصَلِّ بِالنَّاسِ ‏"‏ ‏.‏ قَالَتْ فَقُلْتُ يَا رَسُولَ اللَّهِ إِنَّ أَبَا بَكْرٍ رَجُلٌ رَقِيقٌ إِذَا قَرَأَ الْقُرْآنَ لاَ يَمْلِكُ دَمْعَهُ فَلَوْ أَمَرْتَ غَيْرَ أَبِي بَكْرٍ ‏.‏ قَالَتْ وَاللَّهِ مَا بِي إِلاَّ كَرَاهِيَةُ أَنْ يَتَشَاءَمَ النَّاسُ بِأَوَّلِ مَنْ يَقُومُ فِي مَقَامِ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَتْ فَرَاجَعْتُهُ مَرَّتَيْنِ أَوْ ثَلاَثًا فَقَالَ ‏"‏ لِيُصَلِّ بِالنَّاسِ أَبُو بَكْرٍ فَإِنَّكُنَّ صَوَاحِبُ يُوسُفَ ‏"‏ ‏.‏
Reference : Sahih Muslim 418e
In-book reference : Book 4, Hadith 102
USC-MSA web (English) reference : Book 4, Hadith 836
  (deprecated numbering scheme)