Sayyiduna Uthman (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever prays the 'Isha prayer in congregation, he will have the reward of standing (in prayer) for half the night, and whoever also prays the Fajr prayer in congregation, he will have the reward of standing (in prayer) for the entire night."
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1258
From this hadith, the reward for performing the ‘Isha and Fajr prayers in congregation is understood. Furthermore, it is evident that there is great reward in performing the obligatory (fard) prayers in congregation.
The reward for one prayer is equal to that of 25 or 27 prayers, and there is a severe warning for those who lag behind from the congregation.
The Noble Prophet sallallahu alayhi wa sallam even intended to burn down the houses of those who stay behind from the congregational prayer, as has already been mentioned.