Jesus healed an epileptic boy, and he rebuked his disciples for not having enough faith to do miracles.

Matthew 17:14-21

14 When Jesus and the three disciples returned to the rest of us disciples and to the crowd that had gathered, a man approached Jesus and knelt before him. 15 He said to him, “Sir/Lord, have mercy on my son and heal him! He has epilepsy and suffers very much. Because of this illness, he has fallen in the fire and in the water many times. 16 I brought him to your disciples in order that they might heal him, but they were not able to heal him.” 17 Jesus responded by saying to everyone who had gathered there, “You who have seen how I help people do not believe that you can do anything! Your minds are distorted! How long do I have to be with you before you are able to do what I do [RHQ]? How long do I have to endure your not believing [RHQ]? Bring the boy here to me!” 18 When they brought the boy to Jesus, Jesus rebuked the demon that was causing the epilepsy. As a result, the demon came out of the boy, and right then the boy was healed. 19 Later, some of us disciples approached Jesus. We asked him privately, “Why were we (exc) not able to expel the demon?” 20-21 20-21He answered us, “It is because you did not believe very much in God’s power. Think about this: Mustard seeds are very small, but in this area they grow and produce large [MET] plants. Similarly, if your faith grows until you truly believe that God will do what you ask him to, you will be able to do anything [LIT]! You could even say to this hill, ‘Move from here to there!’ and it would go where you told it to go.”