Stop me if I get out of line, but I'm thinking of Muhammad receiving the Quran in the cave of Hira. It was the angel Gabriel passing it on to him, canon. Gabriel was also the first angel Muhammad saw, and I reckon he's one of the people who can see him in his true form, because Muhammad saw Gabriel's wings shedding jewels. Or so says the hadith? Muhammad and Gabriel interacted, like, a lot. THEY WERE BUDS.

There was also the time when two angels held Muhammad down when he was a kid and soulfisted him, cleansing his heart of evil. I think that was Gabe too, but the two angels thing makes me wanna say it's Cas and Uriel.