Matthew 17:21

19Then the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?”

20He said to them, “Because of your unbelief. For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you.

21But this kind doesn’t go out except by prayer and fasting.”

22While they were staying in Galilee, Jesus said to them, “The Son of Man is about to be delivered up into the hands of men,

23and they will kill him, and the third day he will be raised up.” They were exceedingly sorry.