"And when He came to the disciples, He saw a great multitude around them, and scribes disputing with them. Immediately, when they saw Him, all the people were greatly amazed, and running to Him, greeted Him. And He asked the scribes, 'What are you discussing with them?' Then one of the crowd answered and said, 'Teacher, I brought You my son, who has a mute spirit. And whenever it seizes him, it throws him down; he foams at the mouth, gnashes his teeth, and becomes rigid. So I spoke to Your disciples, that they should cast it out, but they could not.' He answered him and said, 'O faithless generation, how long shall I be with you? How long shall I bear with you? Bring him to Me'" (Mark 9:14-19).
Jesus saw a great multitude around the nine apostles that had been left behind. He also saw the scribes disputing with them. From the following context, one may rightly assume that the scribes had caught the apostles in one--and perhaps the only--instance in which they were not able to miraculously cure someone. Certainly the scribes were making full use of this opportunity to discredit Jesus and His apostles before the crowd by asking sarcastic questions. Their task was even easier since Jesus wasn't there to defend Himself or offer assistance.
It is unknown as to why the people were amazed when they saw Jesus. Many commentators speculate that it was because the face of Jesus shone with remaining traces of His transfiguration glory (e.g., like Moses in Exo. 34:29). However, this view seems unlikely to me since Jesus had desired the event to remain a secret for the time being (cf. Mark 9:9). Also, it is highly doubtful that such a detail would have been left out of the narratives of all three writers describing this event. It seems probable that the amazement was caused by the sudden and appropriately-timed return of Jesus. He showed up at the time when He was needed most. He was needed to help His followers and silence His critics.
Jesus immediately inquired as to what the scribes were discussing with His apostles. Since the scribes did not answer, the father of the demoniac broke the silence and explained to Jesus what was going on. He had brought his child for healing. The child was mute and an epileptic (cf. Matt. 17:15), but these physical ailments seem to be produced by the unclean spirit that possessed him.
"And wherever it seizes him, it throws him down; he foams at the mouth, gnashes his teeth, and becomes rigid" (Mark 9:18). The father described the terrible suffering his boy had been enduring.
The man had brought his son to Jesus for healing, but since He wasn't available at the time, he asked Jesus' disciples to perform the exorcism. The faith of the nine wasn't up to the task (cf. Matt. 17:20). Perhaps they would have been successful if Peter, James, and John had been present; perhaps not.
"O faithless generation, how long shall I be with you? How long shall I bear with you?" (Mark 9:19). Jesus' rebuke here is probably directed to all present: the scribes, the multitude, and even His apostles. Jesus was slowly growing tired of dealing with those who had a weak or non-existent faith. Jesus then confidently requested - "Bring him to Me." Our Lord has no doubt whatsoever that He can heal this child.
We will continue studying this narrative in our next lesson.