14 And when he had arrived at the multitude, a man approached him, falling to his knees before him, saying: "Lord, take pity on my son, for he is an epileptic, and he suffers harm. For he frequently falls into fire, and often also into water.
15 And I brought him to your disciples, but they were not able to cure him."
16 Then Jesus responded by saying: "What an unbelieving and perverse generation! How long shall I be with you? How long shall I endure you? Bring him here to me."
17 And Jesus rebuked him, and the demon went out of him, and the boy was cured from that hour.
18 Then the disciples approached Jesus privately and said, "Why were we unable to cast him out?"
19 Jesus said to them: "Because of your unbelief. Amen I say to you, certainly, if you will have faith like a grain of mustard seed, you will say to this mountain, 'Move from here to there,' and it shall move. And nothing will be impossible for you.
20 But this kind is not cast out, except through prayer and fasting."