Let them be as chaff before the wind - As chaff is driven away in winnowing grain. See the notes at Psalm 1:4.
And let the angel of the Lord chase them - Drive them away, or scatter them. Angels are often represented in the Scriptures as agents employed by God in bringing punishment on wicked people. See 2-Kings 19:35; Isaiah 37:36; 1-Chronicles 21:12, 1-Chronicles 21:30; 2-Samuel 24:16.

Let the angel of the Lord chase them - By angel we may either understand one of those spirits, whether good or bad, commonly thus denominated, or any thing used by God himself as the instrument of their confusion.

Let them be as chaff before the wind: and let the angel of the LORD (d) chase [them].
(d) Smite them with the spirit of giddiness that their enterprises may be foolish, and they received just reward.

Let them be as chaff before the wind,.... As they are; see Psalm 1:4;
and let the angel of the Lord chase them; either a good angel, who is the Lord's, his creature that ministers unto him, and is ready to obey his orders; and who, as he encamps about the saints and protects them, so he is able to destroy their enemies; as one angel in a night destroyed all the firstborn in Egypt, and another the whole army of the Assyrians, Exodus 12:29; an angel of the Lord, who is swift to fly, and so to chase and overtake, and able to execute whatever is the will of the Lord; or else an evil angel, who is the Lord's, being made by him, though not made evil by him; and who is under his restraints, and can do nothing but by his permission; and who sometimes is employed by the Lord, as the executioner of his wrath upon wicked men; is suffered to distress and torture their consciences in this life, and hereafter drag them into everlasting burnings, prepared for the devil and his angels.

(Compare Psalm 1:4) --a terrible fate; driven by wind on a slippery path in darkness, and hotly pursued by supernatural violence (2-Samuel 24:16; Acts 12:23).