Matthew 17:16

And I brought him to thy disciples
To the nine, whilst Christ was with the other three upon the mountain: no doubt but his design was to bring him to Christ first; but he being absent, he applied to his disciples, and, desired them to make use of their power to heal him; and which they attempted, but without success:

and they could not cure him.
This he said, partly to show the malignity and stubbornness of the disease, and partly to accuse the disciples of weakness; when he himself was as much in fault as they, as the following words show. Here the Jew ^F23 insults, and charges with contradiction, that in one place it should be said, that Jesus gave his disciples power to cast out unclean spirits, and here all the disciples could not cast a spirit out of one little child: but without any reason; let it be observed, that "all" the disciples were not present, the three principal ones were with Christ; besides, this was not owing to want of power in them, which Christ had conferred on them, and which they often made use of with success: but partly to their own unbelief, and partly to the unbelief of the father of this child, and others with him, as appears from what follows: and it is clear from Mark, that when he came to Christ, he had but little faith; he says to him, "if thou canst do anything, help us"; and after Christ had talked with him about his faith, he could only say, "Lord, I believe, help mine unbelief".