Call to Prayers (Adhaan)
10/31. Chapter:
Superiority of the Fajr (early morning) prayer in congregation.
Sahih Bukhari
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).
Reference : Sahih al-Bukhari 649In-book reference : Book 10, Hadith 46USC-MSA web (English) reference : Vol. 1, Book 11, Hadith 621