Sahih Muslim , Book 5, Hadith 311 (In-Book) ⓘ
Abu Huraira reported Allah's Messenger as saying: Prayer said in a congregation is equivalent to twenty-five (prayers) as compared with the prayer said by a single person.
وَحَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ بْنِ قَعْنَبٍ، حَدَّثَنَا أَفْلَحُ، عَنْ أَبِي بَكْرِ بْنِ مُحَمَّدِ بْنِ عَمْرِو بْنِ حَزْمٍ، عَنْ سَلْمَانَ الأَغَرِّ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " صَلاَةُ الْجَمَاعَةِ تَعْدِلُ خَمْسًا وَعِشْرِينَ مِنْ صَلاَةِ الْفَذِّ " .
also referenced under: Hadith 649 (Reference) & Book 4, Hadith 1363 (USC-MSA)