Sunan an-Nasa'i, Hadith 838 ⓘ
It was narrated from Abu Hurairah that the Messenger of Allah said: "Praying in congregation is twenty-five portions better than one of you praying alone."
أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " صَلاَةُ الْجَمَاعَةِ أَفْضَلُ مِنْ صَلاَةِ أَحَدِكُمْ وَحْدَهُ خَمْسًا وَعِشْرِينَ جُزْءًا " .
also referenced under: Book 10, Hadith 62 (In-Book) & Volume 1, Book 10, Hadith 839 (DarusSalam)