Matthew 17:14-19

14And when they came to the crowd, a man came to him, falling on his knees before him, and saying,

15Lord, have mercy on my son, for he is lunatic, and suffers sorely; for often he falls into the fire and often into the water.

16And I brought him to thy disciples, and they were not able to heal him.

17And Jesus answering said, O unbelieving and perverted generation, how long shall I be with you? how long shall I bear with you? Bring him here to me.

18And Jesus rebuked him, and the demon went out from him, and the boy was healed from that hour.

19Then the disciples, coming to Jesus apart, said [to him], Why were not we able to cast him out?