كتاب الصلاة
2  
The Book of Prayer
Bulugh al-Maram 398
Narrated 'Abdullah bin 'Umar (RA):
Allah's Messenger (ﷺ) said: "The prayer offered in congregation is twenty-seven degrees more rewardable than a prayer offered by a single person." [Agreed upon].
عَنْ عَبْدِ اَللَّهِ بْنِ عُمَرَ ‏-رَضِيَ اَللَّهُ عَنْهُمَا‏-; أَنَّ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-قَالَ: { صَلَاةُ اَلْجَمَاعَةِ أَفْضَلُ مِنْ صَلَاةِ اَلْفَذِّ بِسَبْعٍ وَعِشْرِينَ دَرَجَةً } مُتَّفَقٌ عَلَيْهِ .‏ 1‏ .‏
Reference : Bulugh al-Maram 398
In-book reference : Book 2, Hadith 398
English translation : Book 2, Hadith 393
Hadith Text
Reference