Mk 9,14-29
As they were rejoining the disciples they saw a large crowd round them and some scribes arguing with them. At once, when they saw him, the whole crowd were struck with amazement and ran to greet him. And he asked them, “What are you arguing about with them?” A man answered him from the crowd, “Master, I have brought my son to you; there is a spirit of dumbness in him, and when it takes hold of him it throws him to the ground, and he foams at the mouth and grinds his teeth and goes rigid. And I asked your disciples to drive it out and they were unable to.”