‘And when he had come into the house his disciples asked him privately, saying, “We could not cast it out.” And he said to them, “This kind can come out by nothing, except by prayer.”
It was always going to happen that the disciples would want to know why they had failed, and they were clearly very disappointed. They had had sufficient faith not to expect to fail. We have here a reminder of the fact that ‘faith' means more than just believing. It involves relationship with God.. But it is emphasised here to bring out the contrast between Jesus Himself and the disciples. He, on the mountain top, in full fellowship with God and revealing the glory of God in Himself, and they below, ineffective because they were not close enough to God. The disciples were not all-powerful, but Jesus was. He alone of all miracle workers and exorcists never failed when people came to Him for help. Jesus will later promise them that they will share this wonderful union with Him and the Father through the Holy Spirit (John 14:18-20; John 14:23; John 15:7).
“This kind can come out by nothing, except by prayer.” We need not doubt that the disciples had prayed, and it is clear that this is not to be taken simply at face value, because Jesus had not prayed, at least not openly. What Jesus meant was that in order to deal with such a powerful and deceitful spirit it was necessary to be in complete union with the Father by a life in which continual prayer was paramount. It was because they were not so in touch with the Father that their faith was too small in this particular case. But for Jesus there had been no problem. He was always in close touch with the Father.