Sunan an-Nasai 15575
In-book no 839أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " صَلاَةُ الْجَمَاعَةِ تَفْضُلُ عَلَى صَلاَةِ الْفَذِّ بِسَبْعٍ وَعِشْرِينَ دَرَجَةً " .
It was narrated from Ibn 'Umar that the Messenger of Allah (ﷺ) said: "Praying in congregation is twenty-seven times better than praying alone."