Mark 6:15

“Others said that it is Elias, etc..] This was the opinion, either of many of the Jews, who expected that Elias the Tishbite would come in person, before the coming of the Messiah; and thought by the appearance and wonderful works of Jesus, that he was now come: or of Herod's courtiers, who said this to divert him from his notion of John the Baptist, which they might perceive was very distressing to him; though the former seems rather to be the sense: others said, that it is a prophet: or “the prophet”, that was to come, whom Moses had spoken of, and the Jews expected; this was the opinion of others of them: or as one of the prophets. The word h, “or”, is left out in some copies; and so it is…”

“See this account of the death of John the Baptist fully explained in the notes at Matthew 14:1-12. Mark 6:20 For Herod feared John - That is, he stood in awe of him on account of his sanctity, and his boldness and fearlessness in reproving sin. Knowing that he was a just man and an Holy - A holy, pious, upright, honest man - a man who would not be afraid of him, or afraid to speak his real sentiments. And observed him - Margin, “kept him, or saved him.” This does not mean that he “observed” or obeyed his teachings, but that he kept him in safe custody in order to preserve him from the machinations of Herodias. He was willing to show his respect for John, and to secure him from danger, and…”

“A prophet, as one of the prophets - Not inferior to one of the ancient prophets. Mark 6:16”

“6:15 The return of the prophet Elijah had been prophesied in Mal 3:1; 4:5-6 (cp. Mark 9:11-13).”

“it is Elias: Mar 8:28, Mar 9:12, Mar 9:13, Mar 15:35, Mar 15:36; Mal 4:5, Elijah, Mat 16:14, Mat 17:10, Mat 17:11; Luk 1:17, Luk 9:8, Luk 9:19; Joh 1:21, Joh 1:25 a prophet: Mat 21:11; Luk 7:16, Luk 7:39; Joh 6:14, Joh 7:40, Joh 9:17; Act 3:22, Act 3:23 Mark 6:16”