Matthew 17:19-21 King James Version (KJV)
19 Then came the disciples to Jesus apart, and said, Why could not we cast him out?
20 And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.
21 Howbeit this kind goeth not out but by prayer and fasting.
Matthew 17:19-21 Amplified Bible, Classic Edition (AMPC)
19 Then the disciples came to Jesus and asked privately, Why could we not drive it out?
20 He said to them, Because of the littleness of your faith [that is, your lack of [a]firmly relying trust]. For truly I say to you, if you have faith [[b]that is living] like a grain of mustard seed, you can say to this mountain, Move from here to yonder place, and it will move; and nothing will be impossible to you.
21 [c]But this kind does not go out except by prayer and fasting.
Matthew 17:19-21 Living Bible (TLB)
19 Afterwards the disciples asked Jesus privately, “Why couldn’t we cast that demon out?”
20 “Because of your little faith,” Jesus told them. “For if you had faith even as small as a tiny mustard seed, you could say to this mountain, ‘Move!’ and it would go far away. Nothing would be impossible. 21 But this kind of demon won’t leave unless you have prayed and gone without food.”[a]