Narrated Abu Salama bin `Abdur Rahman
Abu Huraira said, "I heard Allah's Messenger (ﷺ) saying, 'The reward of a prayer in congregation is twenty five times greater than that of a prayer offered by a person alone. The angels of the night and the angels of the day gather at the time of Fajr prayer.' " Abu Huraira then added, "Recite the Holy Book if you wish, for "Indeed, the recitation of the Qur'an in the early dawn (Fajr prayer) is ever witnessed." (17:78).
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).
Narrated Salim
I heard Um Ad-Darda' saying, "Abu Ad-Darda' entered the house in an angry mood. I said to him. 'What makes you angry?' He replied, 'By Allah! I do not find the followers of Muhammad doing those good things (which they used to do before) except the offering of congregational prayer." (This happened in the last days of Abu Ad-Darda' during the rule of `Uthman).
Narrated Abu Musa
The Prophet (ﷺ) said, "The people who get tremendous reward for the prayer are those who are farthest away (from the mosque) and then those who are next farthest and so on. Similarly one who waits to pray with the Imam has greater reward than one who prays and goes to bed. "