While he was coming, the demon threw him to the ground and convulsed him. But Jesus rebuked the unclean spirit and healed the boy, and gave him back to his father.
This passage of story in Matthew and Mark follows immediately upon that of Christ's transfiguration, and his discourse with his disciples after it; but here it is said to be on the next day, as they were coming down from the hill, which confirms the conjecture that Christ was transfigured in the night, and, it should seem, though they did not make tabernacles as Peter...
Commenting on Luke 9:37-42
But they understood not this saying,.... What was meant by being betrayed into the hands of men, and by his being put to death; they knew not, how these things could possibly be, for they could not by any means reconcile them with the notions they had of a temporal Redeemer, and victorious Messiah: and it was hid from them, that they perceived it not...
The devil threw him down, and tare him - See this case considered at large, on Mat 17:15-18 (note), and on Mar 9:14-27 (note).