Hadith 1473
Sayyiduna Uthman bin Affan (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs the ‘Isha prayer in congregation, it is as if he has performed tahajjud for half the night. And whoever performs the Fajr prayer in congregation, it is as if he has performed tahajjud for the entire night."