Abu Hurayrah (may Allah be pleased with him) says that I heard the Messenger of Allah (peace and blessings be upon him) say: "Offering the prayer in congregation is superior to the prayer of a man alone by twenty-five degrees. The angels of the night and the angels of the day gather at the Fajr prayer." Abu Hurayrah (may Allah be pleased with him) said: "If you wish, recite: 'And (recite) the Qur'an of Fajr; indeed the recitation of Fajr is witnessed (by the angels)' [Surah al-Isra: 78]."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4960