Mark 9:28

“And when he was come into the house, etc..] Perhaps into the man's house whose child he had healed, or into some other in these parts, for the sake both of retirement and refreshment: his disciples asked him privately, why could not we cast him out? The nine disciples, who were particularly concerned in this matter, fearing they had lost the power of casting out devils, conferred upon them, inquired of Jesus, when he was alone, why they could not cast the demon out of the child, when they had ejected unclean spirits out of many others; (see Gill on “<401719>Matthew 17:19”).”

“See this passage explained in the notes at Matthew 17:14-21. Mark 9:14 Questioning with them - Debating with the disciples, and attempting to confound them. This he saw as he came down from the mount. In his absence they had taken occasion to attempt to perplex and confound his followers. Mark 9:15 Were greatly amazed - Were astonished and surprised at his sudden appearance among them. Saluted him - Received him with the customary marks of affection and respect. It is probable that this was not by any “formal” manner of salutation, but by the “rush” of the multitude, and by hailing him as the Messiah. Mark 9:16 What question ye? - What is the subject of your inquiry or debate with the…”

“9:28-29 The account ends, surprisingly, by stressing the importance of prayer rather than of faith (cp. 11:22-24).”

“asked: Mar 4:10, Mar 4:34; Mat 13:10, Mat 13:36, Mat 15:15 Why: Mat 17:19, Mat 17:20 Mark 9:29”