MATTHEW 17.19-21
Then the disciples having come to Jesus by Himself, said, “Why were we not able to cast him out?” And Jesus said to them, “Through your want of faith; for truly I say to you, if you may have faith as a grain of mustard, you will say to this mountain, Move from here to there, and it will move, and nothing will be impossible to you, [[and this kind does not go forth except in prayer and fasting.”]]