When they came to the crowd, a man met Jesus. He knelt before him,
saying, "Lord, show mercy to my son. He is epileptic and suffers terribly, for he often falls into the fire or the water.
I brought him to your disciples, but they couldn't heal him."
Jesus answered, "You faithless and crooked generation, how long will I be with you? How long will I put up with you? Bring the boy here to me."
Then Jesus spoke harshly to the demon. And it came out of the child, who was healed from that time on.
Then the disciples came to Jesus in private and said, "Why couldn't we throw the demon out?"
"Because you have little faith," he said. "I assure you that if you have faith the size of a mustard seed, you could say to this mountain, ‘Go from here to there,' and it will go. There will be nothing that you can't do."