14 And when they had come to the multitude, a man came to Him, kneeling down to Him and saying, 15 "Lord, have mercy on my son, for he is an epileptic and suffers severely; for he often falls into the fire and often into the water. 16 So I brought him to Your disciples, but they could not cure him." 17 Then Jesus answered and said, "O faithless and perverse generation, how long shall I be with you? How long shall I bear with you? Bring him here to Me." 18 And Jesus rebuked the demon, and it came out of him; and the child was cured from that very hour. 19 Then the disciples came to Jesus privately and said, "Why could we not cast it out?" 20 So Jesus said to them, "Because of your unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, 'Move from here to there,' and it will move; and nothing will be impossible for you.
Matthew Henry's Commentary on Matthew 17:14-20
Commentary on Matthew 17:14-21
(Read Matthew 17:14-21)
The case of afflicted children should be presented to God by faithful and fervent prayer. Christ cured the child. Though the people were perverse, and Christ was provoked, yet care was taken of the child. When all other helps and succours fail, we are welcome to Christ, may trust in him, and in his power and goodness. See here an emblem of Christ's undertaking as our Redeemer. It encourages parents to bring children to Christ, whose souls are under Satan's power; he is able to heal them, and as willing as he is able. Not only bring them to Christ by prayer, but bring them to the word of Christ; to means by which Satan's strong-holds in the soul are beaten down. It is good for us to distrust ourselves and our own strength; but it is displeasing to Christ when we distrust any power derived from him, or granted by him. There was also something in the malady which rendered the cure difficult. The extraordinary power of Satan must not discourage our faith, but quicken us to more earnestness in praying to God for the increase of it. Do we wonder to see Satan's bodily possession of this young man from a child, when we see his spiritual possession of every son of Adam from the fall!