Sahih Muslim
Sahih Muslim 473
وَحَدَّثَنِي أَبُو بَكْرِ بْنُ نَافِعٍ الْعَبْدِيُّ، حَدَّثَنَا بَهْزٌ، حَدَّثَنَا حَمَّادٌ، أَخْبَرَنَا ثَابِتٌ، عَنْ أَنَسٍ، قَالَ مَا صَلَّيْتُ خَلْفَ أَحَدٍ أَوْجَزَ صَلاَةً مِنْ صَلاَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي تَمَامٍ كَانَتْ صَلاَةُ رَسُولِ اللَّهِ صلى الله عليه وسلم مُتَقَارِبَةً وَكَانَتْ صَلاَةُ أَبِي بَكْرٍ مُتَقَارِبَةً فَلَمَّا كَانَ عُمَرُ بْنُ الْخَطَّابِ مَدَّ فِي صَلاَةِ الْفَجْرِ وَكَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا قَالَ " سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ " . قَامَ حَتَّى نَقُولَ قَدْ أَوْهَمَ . ثُمَّ يَسْجُدُ وَيَقْعُدُ بَيْنَ السَّجْدَتَيْنِ حَتَّى نَقُولَ قَدْ أَوْهَمَ .
Anas reported: I never prayed behind anyone whose prayer was briefer yet more complete than the prayer of the Messenger of Allah ﷺ. His prayer and the prayer of Abu Bakr were similar in length. When Umar ibn al-Khattab became leader, he lengthened the Fajr prayer. When the Messenger of Allah ﷺ said Allah hears whoever praises Him, he would stand until we thought he had forgotten, then prostrate and sit between the two prostrations until we thought he had forgotten.