Mark 9:18, 20

When the spirit attacks him, it throws him on the ground. Then my son foams at the mouth, grinds his teeth, and becomes very stiff. I asked your followers to force the evil spirit out, but they couldn’t.”

So the followers brought him to Jesus. As soon as the evil spirit saw Jesus, it made the boy lose control of himself, and he fell down and rolled on the ground, foaming at the mouth.