Mark 9:23 (KJV)

And wheresoever he taketh him, he teareth him: and he foameth, and gnasheth with his teeth, and pineth away: and I spake to thy disciples that they should cast him out; and they could not.

He answereth him, and saith, O faithless generation, how long shall I be with you? how long shall I suffer you? bring him unto me.

And they brought him unto him: and when he saw him, straightway the spirit tare him; and he fell on the ground, and wallowed foaming.

And he asked his father, How long is it ago since this came unto him? And he said, Of a child.

And ofttimes it hath cast him into the fire, and into the waters, to destroy him: but if thou canst do any thing, have compassion on us, and help us.

And straightway the father of the child cried out, and said with tears, Lord, I believe; help thou mine unbelief.

When Jesus saw that the people came running together, he rebuked the foul spirit, saying unto him, Thou dumb and deaf spirit, I charge thee, come out of him, and enter no more into him.

And the spirit cried, and rent him sore, and came out of him: and he was as one dead; insomuch that many said, He is dead.

But Jesus took him by the hand, and lifted him up; and he arose.

And when he was come into the house, his disciples asked him privately, Why could not we cast him out?