Matthew 17:14-20

¹⁴When they came to the crowd, a man came up to Jesus, falling on his knees before Him and saying, ¹⁵“Lord, have mercy on my son, for he is a lunatic and is very ill; for he often falls into the fire and often into the water. ¹⁶I brought him to Your disciples, and they could not cure him.” ¹⁷And Jesus answered and said, “You unbelieving and perverted generation, how long shall I be with you? How long shall I put up with you? Bring him here to Me.” ¹⁸And Jesus rebuked him, and the demon came out of him, and the boy was cured at once.

¹⁹Then the disciples came to Jesus privately and said, “Why could we not drive it out?” ²⁰And He said to them, “Because of the littleness of your faith; for truly I say to you, if you have faith the size of a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible to you.