Hadith
Uthman bin Affan narrated that:
Allah's Messenger said: "Whoever attends Isha (prayer) in congregation, then he has (the reward as if he had) stood half of the night. And whoever prays Isha and Fajr in congregation, then he has (the reward as if he had) spend the entire night standing (in prayer)."
Authentic
Jami` at-Tirmidhi