Matthew
Matthew 17:19BSB·traditional attribution

Afterward the disciples came to Jesus privately and asked, “Why couldn’t we drive it out?”

John Calvin Reformed @genevareformer

Matthew 17:19. Then the disciples coming. The disciples wonder that the power which they once possessed has been taken from them; but they had lost it by their own fault. Christ therefore attributes this want of ability to their unbelief, and repeats and illustrates more largely the statement which he had previously made, that nothing is impossible to faith It is a hyperbolical mode of...

Matthew Henry Presbyterian @wholebiblehenry

We have here the miraculous cure of a child that was lunatic and vexed with a devil. Observe, I. A melancholy representation of the case of this child, made to Christ by the afflicted father. This was immediately upon his coming down from the mountain where he was transfigured. Note, Christ's glories do not make him unmindful of us and of our wants and miseries.

Commenting on Matthew 17:14-21

John Gill Reformed Baptist @doctorgill

Then came the disciples to Jesus apart,.... Or "secretly", as the Vulgate Latin, and Munster's Hebrew Gospel read; that is, privately, and when alone; and as Mark says, "when he was come into the house"; and was by himself, then came the nine disciples to him, to converse with him about this matter, and said unto him, why could not we cast him out?