صَحِيحُ الْبُخَارِيِّ
Sahih al-Bukhari 649
Call to Prayers (Adhaan)
Superiority of the Fajr (early morning) prayer in congregation.
قَالَ شُعَيْبٌ وَحَدَّثَنِي نَافِعٌ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، قَالَ تَفْضُلُهَا بِسَبْعٍ وَعِشْرِينَ دَرَجَةً.
Narrated `Abdullah bin `Umar: The reward of the congregational prayer is twenty seven times greater (than that of the prayer offered by a person alone).
Sahih al-Bukhari, 649Sahihصحيح