Sahih al-Bukhari, Volume 1, Book 11, Hadith 621 (USC-MSA) ⓘ

Narrated Abu Salama bin `Abdur Rahman: Abu Huraira said, "I heard Allah's Messenger saying, 'The reward of a prayer in congregation is twenty five times greater than that of a prayer offered by a person alone. The angels of the night and the angels of the day gather at the time of Fajr prayer.' " Abu Huraira then added, "Recite the Holy Book if you wish, for "Indeed, the recitation of the Qur'an in the early dawn (Fajr prayer) is ever witnessed." (17:78).

حَدَّثَنَا أَبُو الْيَمَانِ، قَالَ أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، قَالَ أَخْبَرَنِي سَعِيدُ بْنُ الْمُسَيَّبِ، وَأَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ أَنَّ أَبَا هُرَيْرَةَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏"‏ تَفْضُلُ صَلاَةُ الْجَمِيعِ صَلاَةَ أَحَدِكُمْ وَحْدَهُ بِخَمْسٍ وَعِشْرِينَ جُزْءًا، وَتَجْتَمِعُ مَلاَئِكَةُ اللَّيْلِ وَمَلاَئِكَةُ النَّهَارِ فِي صَلاَةِ الْفَجْرِ ‏"‏‏.‏ ثُمَّ يَقُولُ أَبُو هُرَيْرَةَ فَاقْرَءُوا إِنْ شِئْتُمْ ‏{‏إِنَّ قُرْآنَ الْفَجْرِ كَانَ مَشْهُودًا‏}‏

Narrated `Abdullah bin `Umar: The reward of the congregational prayer is twenty seven times greater (than that of the prayer offered by a person alone).

قَالَ شُعَيْبٌ وَحَدَّثَنِي نَافِعٌ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ تَفْضُلُهَا بِسَبْعٍ وَعِشْرِينَ دَرَجَةً‏.‏