the Messenger of Allah said: "Whoever prays Fajr in congregation, then sits remembering Allah until the sun has risen, then he prays two Rak'ah, then for him is the reward like that of a Hajj and Umrah." He said: "The Messenger of Allah said: 'Complete, complete, complete.'"
Jami` at-Tirmidhi Book 6, Hadith 43