Language:
كتاب الأذان
10  
Call to Prayers (Adhaan)
(46)
Chapter: The religious learned men are entitled to precedence in leading the Salat (prayer)
(46)
باب أَهْلُ الْعِلْمِ وَالْفَضْلِ أَحَقُّ بِالإِمَامَةِ
Sahih al-Bukhari 681

Narrated Anas:

The Prophet (ﷺ) did not come out for three days. The people stood for the prayer and Abu Bakr went ahead to lead the prayer. (In the meantime) the Prophet (ﷺ) caught hold of the curtain and lifted it. When the face of the Prophet (ﷺ) appeared we had never seen a scene more pleasing than the face of the Prophet (ﷺ) as it appeared then. The Prophet (ﷺ) beckoned to Abu Bakr to lead the people in the prayer and then let the curtain fall. We did not see him (again) till he died.

حَدَّثَنَا أَبُو مَعْمَرٍ، قَالَ حَدَّثَنَا عَبْدُ الْوَارِثِ، قَالَ حَدَّثَنَا عَبْدُ الْعَزِيزِ، عَنْ أَنَسٍ، قَالَ لَمْ يَخْرُجِ النَّبِيُّ صلى الله عليه وسلم ثَلاَثًا، فَأُقِيمَتِ الصَّلاَةُ، فَذَهَبَ أَبُو بَكْرٍ يَتَقَدَّمُ فَقَالَ نَبِيُّ اللَّهِ صلى الله عليه وسلم بِالْحِجَابِ فَرَفَعَهُ، فَلَمَّا وَضَحَ وَجْهُ النَّبِيِّ صلى الله عليه وسلم مَا نَظَرْنَا مَنْظَرًا كَانَ أَعْجَبَ إِلَيْنَا مِنْ وَجْهِ النَّبِيِّ صلى الله عليه وسلم حِينَ وَضَحَ لَنَا، فَأَوْمَأَ النَّبِيُّ صلى الله عليه وسلم بِيَدِهِ إِلَى أَبِي بَكْرٍ أَنْ يَتَقَدَّمَ، وَأَرْخَى النَّبِيُّ صلى الله عليه وسلم الْحِجَابَ، فَلَمْ يُقْدَرْ عَلَيْهِ حَتَّى مَاتَ‏.‏
Reference : Sahih al-Bukhari 681
In-book reference : Book 10, Hadith 75
USC-MSA web (English) reference : Vol. 1, Book 11, Hadith 649
  (deprecated numbering scheme)