Anas bin Malik رضي الله عنه narrated that : the Messenger of Allah صلى الله عليه و سلم 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 صلى الله عليه و سلم said:
‘Complete, complete, complete.'”
Jami` at-Tirmidhi 586. Classed it as hasan by Shyakh al-Albaani in Saheeh Sunan al-Tirmidhi.