Sayyiduna Jabir (may Allah be pleased with him) said: I never saw the Messenger of Allah (peace and blessings be upon him) rise from the place where he had offered the Fajr prayer until the sun had risen; then he (peace and blessings be upon him) would rise.
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2000