Immediately after recounting the mount of transfiguration, Mark provides the following account:
Mark 9:14-29 (KJV)
And when he came to his disciples, he saw a great multitude about them, and the scribes questioning with them. And straightway all the people, when they beheld him, were greatly amazed, and running to him saluted him. And he asked the scribes, "What question ye with them?"
And one of the multitude answered and said, "Master, I have brought unto thee my son, which hath a dumb spirit; 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."
Jesus said unto him, "If thou canst believe, all things are possible to him that believeth."
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?"
And he said unto them, "This kind can come forth by nothing, but by prayer and fasting."
Mark 9:14-29 (ESV)
And when they came to the disciples, they saw a great crowd around them, and scribes arguing with them. And immediately all the crowd, when they saw him, were greatly amazed and ran up to him and greeted him. And he asked them, “What are you arguing about with them?”
And someone from the crowd answered him, “Teacher, I brought my son to you, for he has a spirit that makes him mute. And whenever it seizes him, it throws him down, and he foams and grinds his teeth and becomes rigid. So I asked your disciples to cast it out, and they were not able.”
And he answered them, “O faithless generation, how long am I to be with you? How long am I to bear with you? Bring him to me.” And they brought the boy to him. And when the spirit saw him, immediately it convulsed the boy, and he fell on the ground and rolled about, foaming at the mouth. And Jesus asked his father, “How long has this been happening to him?”
And he said, “From childhood. And it has often cast him into fire and into water, to destroy him. But if you can do anything, have compassion on us and help us.”
And Jesus said to him, “‘If you can’! All things are possible for one who believes.”
Immediately the father of the child cried out and said, “I believe; help my unbelief!”
And when Jesus saw that a crowd came running together, he rebuked the unclean spirit, saying to it, “You mute and deaf spirit, I command you, come out of him and never enter him again.”
And after crying out and convulsing him terribly, it came out, and the boy was like a corpse, so that most of them said, “He is dead.”
But Jesus took him by the hand and lifted him up, and he arose. And when he had entered the house, his disciples asked him privately, “Why could we not cast it out?”
And he said to them, “This kind cannot be driven out by anything but prayer.”
My initial thought was that possibly this was just a case of so-called parallel corruption, where the "and fasting" was probably borrowed from the account in another Gospel. And indeed, in Matthew 17:21 the KJV has "prayer and fasting." The full account there is as follows:
Matthew 17:14-21 (KJV)However, it turns out that the final verse of this passage is entirely omitted in the ESV:
And when they were come to the multitude, there came to him a certain man, kneeling down to him, and saying, "Lord, have mercy on my son: for he is lunatick, and sore vexed: for ofttimes he falleth into the fire, and oft into the water. And I brought him to thy disciples, and they could not cure him."
Then Jesus answered and said, "O faithless and perverse generation, how long shall I be with you? how long shall I suffer you? bring him hither to me." And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour.
Then came the disciples to Jesus apart, and said, "Why could not we cast him out?"
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. Howbeit this kind goeth not out but by prayer and fasting."
Matthew 17:14-20 (there is no 21) (ESV)
And when they came to the crowd, a man came up to him and, kneeling before him, said, “Lord, have mercy on my son, for he is an epileptic and he suffers terribly. For often he falls into the fire, and often into the water. And I brought him to your disciples, and they could not heal him.”
And Jesus answered, “O faithless and twisted generation, how long am I to be with you? How long am I to bear with you? Bring him here to me.” And Jesus rebuked the demon, and it came out of him, and the boy was healed instantly.
Then the disciples came to Jesus privately and said, “Why could we not cast it out?”
He said to them, “Because of your little faith. For truly, I say to you, if you have faith like a grain of mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move, and nothing will be impossible for you.”
This account is also in Luke's gospel, but lacks any comment about prayer and/or fasting, in both the KJV and the ESV.
The significance of all this is that in the ESV, the "fasting" reference is entirely gone. With the "fasting" reference gone, Jesus' comments at Mark 9:29 become more clear.
Jesus said, “This kind cannot be driven out by anything but prayer.” But where is prayer in this passage? Jesus simply rebukes the spirit and the spirit comes out. Jesus does not pray to the Father. Nor in the immediate context had Jesus been involved in prayer. Who then had prayed? The answer becomes clear in the context. The person praying is the father of the demoniac, and he was praying to Jesus.
Notice the indicia of prayer: the expression of faith and the entreaty in Mark's immediate context. Moreover, we find further confirmation of this from the kneeling posture and the reference to Jesus as "Lord," in Matthew's account (neither of which are mentioned in Mark's account).
Thus, not only does Jesus receive prayer (which is something that God alone should receive), he attributes the success of this miracle to the prayer offered to him by the demoniac's father!
Is this a lock-tight argument in every aspect? Obviously not. The argument relies in part on a question of a textual variant. Moreover, while the most apparent reference to prayer in the context is the father's prayer to Jesus, one could interpret this text as suggesting that Jesus had a life of prayer that the nine disciples did not. Indeed, if the text "and fasting," is not original, it would certainly seem as though the scribe who inserted it had that kind of understanding of the text.
Nevertheless, despite not being a fully lock-tight argument as to the variant verse, it still remains the case that Jesus received prayer, that Jesus accepted that prayer without rebuking the man who prayed to him, and that God's response to the prayer was to answer it with healing. That part of the argument stands in both the KJV and the ESV. So, the only difference between the two is that the ESV provides a little extra evidence for the divinity of Christ - something we hardly need (given the superabundance of such evidence in the Bible) but something we can still treasure.