Sunan Ibn Majah, Book 4, Hadith 52 (In-Book) ⓘ
It was narrated that Abu Hurairah said: "The Messenger of Allah said: 'A man's prayer in congregation is twenty-some levels higher than his prayer in his house or in the marketplace.'"
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " صَلاَةُ الرَّجُلِ فِي جَمَاعَةٍ تَزِيدُ عَلَى صَلاَتِهِ فِي بَيْتِهِ وَصَلاَتِهِ فِي سُوقِهِ بِضْعًا وَعِشْرِينَ دَرَجَةً " .
also referenced under: Hadith 786 (Reference) & Volume 1, Book 4, Hadith 786 (DarusSalam)