Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Bukhari :: Book 5 :: Volume 59 :: Hadith 327
Narrated Rifaa:
(who was one of the Badr warriors) Gabriel came to the Prophet and said, "How do you look upon the warriors of Badr among yourselves?" The Prophet said, "As the best of the Muslims." or said a similar statement. On that, Gabriel said, "And so are the Angels who participated in the Badr (battle)."