Mark 9:18, 20

Whenever the demon takes control of him, it knocks him down, and he foams at the mouth and gnashes his teeth, and his body becomes stiff as a board. I brought him to your disciples, hoping they could deliver him, but they were not able to do it.”

So they brought him to Jesus. As soon as the demon saw him, it threw the boy into convulsions. He fell to the ground, rolling around and foaming at the mouth.