"Behold, I will send my messenger": God answers that he is coming to show himself the God of judgment and justice. Are they ready to meet him and to bear his sentence? Who this "messenger" is disputed. That no angel or heavenly visitant is meant is clear from historical considerations, as no such event took place immediately before the Lord came to his temple. Nor can Malachi himself be intended, as his message was delivered nearly four hundred years before Messiah came. The announcement is doubtless founded upon, and refers to the same person as the older prophet mentions, who is generally allowed to be John the Baptist, the herald of Christ's advent.
"Prepare the way before me" The expression is borrowed from . He prepares the way by preaching repentance, and thus removing the obstacle of sin which stood between God and his people. Luke 1:76. The prophecy on John the Baptist's birth: "Thou, child, shalt be called the prophet of the Highest, for thou shalt go before the face of the Lord to prepare His way, to give knowledge of salvation unto His people, for the remission of their sins." Repentance was to be the preparation for the kingdom of Christ, the Messiah, for whom they looked so impatiently.
"And the Lord, whom ye seek": The Lord is Jehovah, as in Exodus 23:17; Isaiah 1:24; Isaiah 3:1, etc. There is a change of persons here, as frequently. This is the person himself speaking, the Son of God, and promised Messiah, the Lord of all men, and particularly of his church and people, in right of marriage, by virtue of redemption, and by being their Head and King; so Kimchi and Ben Melech interpret it of him, and even Abarbinel himself; the Messiah that had been so long spoken of and so much expected, and whom the Jews sought after, either in a scoffing manner, expressed in the above question, or rather seriously; some as a temporal deliverer, to free them from the Roman yoke, and bring them into a state of liberty, prosperity, and grandeur; and others as a spiritual Saviour, to deliver from sin, law, hell, and death, and save them with an everlasting salvation.
"Shall suddenly come to his temple": Jehovah shall unexpectedly come to his temple as King and God of Israel. There was a literal fulfilment of this prophecy when Christ was presented in the temple as an infant.
"suddenly" — This epithet marks the second coming, rather than the first; the earnest of that unexpected coming to judgment was given in the judicial expulsion of the money-changing profaners from the temple by Messiah, where also as here He calls the temple His temple. Also in the destruction of Jerusalem, most unexpected by the Jews, who to the last deceived themselves with the expectation that Messiah would suddenly appear as a temporal Saviour. Compare the use of "suddenly" in Numbers 12:4-10, where He appeared in wrath.
