3:1 my messenger. See 4:5; also Is. 40:3 (where “prepare the way” also occurs). It was the practice in the Near East to send messengers in advance of a visiting king to announce his coming and to remove all hindrances or obstacles. This messenger (Matt. 11:10) will be the last of his kind to appear before the coming of the Lord, who is “the messenger of the covenant.”

suddenly. This word is almost always associated in Scripture with an unhappy and calamitous circumstance (Num. 12:4; Is. 47:11; cf. 2 Pet. 3:10).

the messenger of the covenant. A person distinct from “my messenger,” He will purify the sacrifices, the priests, and the nation (vv. 2–5). This “messenger of the covenant” is the Messiah, and this prophecy is fulfilled in Jesus who alone has performed the perfect sacrifice on behalf of His people.