These men are genuinely puzzled. They have heard their teacher speak of a Son of man who is bound to suffer (8:31) before he receives the crown (8:38). They have just seen his splendor on the mountain and heard the heavenly voice booming out of the cloud (9:7), telling them that the prophet of Nazareth is greater than the greatest man of their ancestral religion, Moses. The two chief men of the OT retire and disappear, and their master is left alone in solitary
Mark 9:9–10