Mark 9:29

“And he said unto them, etc..] Matthew, besides the following reason, assigns another, as given by our Lord, why they could not cast out the foul spirit, which was their unbelief; of which they were guilty in some sort, as well as the Jews, and the father of the child; but Mark omits it, and only relates this as the reason; this kind can come forth by nothing, but by prayer and fasting; which they had not observed; (see Gill on “<401721>Matthew 17:21”).”

“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…”

“This: Mat 12:45; Luk 11:26 by prayer: Kg1 17:20-22; Kg2 4:33, Kg2 4:34; Mat 17:21; Act 9:40, Act 9:41; Co2 12:8; Eph 6:18; Jam 5:15 fasting: Dan 9:3; Act 14:23; Co1 9:27; Co2 6:5, Co2 11:27 Mark 9:30”