Charles Ellicott Commentary Malachi 4:5

"Behold, I will send you Elijah the prophet before the great and terrible day of Jehovah come." — Malachi 4:5 (ASV)

Elijah. —There is no more reason to suppose that this refers actually to “Elijah” the prophet, and that he is to appear upon earth, than to imagine from Hosea 3:5; Ezekiel 24:23; Ezekiel 37:24; Jeremiah 30:9, that David himself is to come again in the flesh. When John the Baptist answered the question of the deputies of the Sanhedrin, Art thou Elias? by I am not, he simply gave a negative reply to their question, which was formulated on their misapprehension. On the other hand, that John the Baptist is the “messenger” of Malachi 3:1 and the “Elijah” of this verse is shown conclusively (as far as Christians are concerned) by Luke 1:16-17 before his birth; by Matthew 3:1-12, Mark 1:2–8, and Luke 3:2-18, at the commencement of his ministry.

Moreover, our Lord Himself assured the people that John was this “messenger” and “Elijah” (Matthew 11:10 and following; Luke 7:27 and following), and His disciples that he had appeared, and not been recognized (Matthew 17:11 and following; Mark 9:1 and following). Finally, it is a significant fact that these two greatest of Old Testament prophets, Moses and Elias, who are mentioned together in this last prophetic exhortation, are the two who appeared with Christ on the Mount of Transfiguration, when all that is contained in the Law and the prophets was about to be fulfilled.