And you, child, will be called a prophet of the Most High; for you will go on before the Lord to prepare the way for Him, to give to His people the knowledge of salvation through the forgiveness of their sins, because of the tender mercy of our God, by which the Dawn will visit us from on high, to shine on those who live in darkness and in the shadow of death, to guide our feet into the path of peace.”
"Behold, I will send My messenger, who will prepare the way before Me. Then the Lord whom you seek will suddenly come to His temple—the Messenger of the covenant, in whom you delight—see, He is coming," says the LORD of Hosts.
Significance
Zechariah's Benedictus applies the herald-prophecy prospectively to the infant John: "you will go on before the Lord to prepare the way for Him" (Luke 1:76) verbally fuses Isaiah 40:3's "prepare the way of the LORD" with Malachi 3:1's "he will prepare the way before me" — the same composite herald-chain (Exod 23:20 → Isa 40:3 → Mal 3:1) that Mark 1:2-3 will later cite explicitly. Where Luke 3:4-6 and John 1:23 deploy Isaiah 40:3 retrospectively at the threshold of John's adult ministry, Luke 1:76 deploys it prospectively at his birth, on the lips of his own father, so that John's entire vocation is framed from the cradle as the Isaianic-Malachian forerunner. The "Lord" before whom John goes is, in the immediate context, the LORD of Israel; in Luke's narrative it is the Christ in Mary's womb — another quiet Yahweh-Christology, since the way prepared for Yahweh in Isaiah is the way prepared for Jesus in Luke. The connection is Promise-Fulfillment by way of allusion: no citation formula, but unmistakable verbal dependence on the herald-texts. The telos is not John's greatness as prophet but the dawn he announces — "the Dawn will visit us from on high… to guide our feet into the path of peace" (Luke 1:78-79) — for the forerunner exists only to make visible and desirable the rising Sun of righteousness whose coming is mercy (cf. Mal 4:2). John is the voice; Christ is the glory the voice exists to reveal.