Verses 1-3
Isaiah 31:1-3. Wo to them that go down to Egypt, &c. — As the Jews did, contrary to God’s command, Deuteronomy 17:16. And stay on horses — For Egypt had many and choice horses. But they look not unto the Lord — Their confidence in the creature was accompanied with, and produced, a distrust of God, and a neglect of seeking to him by prayer for his help. Yet he also is wise, &c. — You think you are wise, in engaging the Egyptians; but God is not inferior to them in wisdom or strength, but much superior, and therefore you have done foolishly in preferring them before him, who will execute his judgments upon you, notwithstanding all the Egyptians can do. And will not call back his words — His threatenings denounced against you; but will arise against the evil-doers — Against this wicked and rebellious people; and against the help — That is, the helpers, as it is explained in the next verse; of them that work iniquity — That act in direct opposition to the express command of God. The Egyptians are men, and not God — And therefore are utterly unable to defend you, either without or against God’s will; and their horses, flesh — Weak and frail, and not spirit — Not like spiritual substances, such as the angels, who are immortal, and invisible to men. When the Lord shall stretch out his hand — Shall exert his power to oppose or punish them, both he that helpeth and he that is holpen shall fall, &c., together — And their alliance shall prove their joint ruin.

Verse 4-5
Isaiah 31:4-5. For, or but or, nevertheless, thus hath the Lord spoken — That is, although you have done evil in sending to Egypt for help, and they will not be able to help you, yet the Lord will of his own grace, and for the glory of his own name, give you that help and deliverance which you do not deserve, and had no reason to expect from him. Like as the lion roaring on his prey — When he is ready to seize upon and devour it; he will not be afraid, nor abase himself — So as to be in the least moved, either to quit his prey, or to make any more haste than otherwise he would do in seizing it. So shall the Lord of hosts fight for mount Zion — With such an unshaken and undaunted resolution, not to be moved by any opposition: and he will as easily and irresistibly destroy the Assyrian army, as a lion tears a lamb in pieces. As birds flying, &c. — Which come from above, and so cannot be kept off; which fly swiftly, and engage themselves readily and resolutely, when they perceive their young ones are in danger. Bishop Lowth renders the clause, As the mother birds hovering over their young; so shall Jehovah, God of hosts, protect Jerusalem — With such care and compassion, such swiftness and resolution. Defending also he will deliver it — That is, he will so defend it as to secure the continuance of its safety, and not suffer it to fall into the enemy’s hand. And passing over he will preserve it — The word פסוח, here rendered passing over, is the word constantly used of the destroying angel’s passing over the houses of the Israelites, when he slew all the firstborn of the Egyptians, (Exodus 12.,) to which history the prophet seems here to refer. The destroying angel was to pass over Jerusalem, and leave it untouched, although it deserved to be destroyed, and was only to smite the Assyrian army. The besiegers were to be slain by the pestilence, but none of the besieged were to take the infection.

Verse 6-7
Isaiah 31:6-7. Turn ye unto him, &c. — Let the consideration of this gracious promise engage you to repent of all your sins, and among the rest, of your carnal policies in seeking and trusting to Egypt for help, and sincerely to return to God. From whom the children of Israel — From whom not only the Israelites, strictly so called, those of the ten tribes, but from whom you of the two tribes, you Jews, who are also the children of Israel, and therefore are under very great obligations to God, have deeply revolted — In your hearts and lives, your affections being alienated from him, and set upon your sins and idols, and your actions a scene of disobedience to his laws. For in that day — When the Assyrian shall invade your land; every man shall cast away his idols — You shall find the vanity of those idols to which you have trusted; and therefore shall cast them away with indignation, and be forced to seek to Jehovah for help; which your hands have made unto you for sin — That is, as instruments of your sin of idolatry, and of many other sins connected therewith.

Verse 8-9
Isaiah 31:8-9. Then shall the Assyrian, &c. — When you have cast away your idols, and seriously sought unto God for help; both which things were performed by Hezekiah; fall by the sword, not of a mighty man, &c. — Not of any man, mean or mighty, but of an angel. But he shall flee from the sword — From, or for fear of, that plague, which so strangely and suddenly destroyed his army. And his young men — Hebrew, בחוריו, his choice young men, his guards, and valiant commanders, and soldiers, shall be discomfited — Hebrew, למס יהיו, shall be for melting, or shall melt away; a great part of them being destroyed by the angel, and the hearts of the rest melting for fear. And he shall pass to his stronghold — Sennacherib shall flee away with all speed from Jerusalem, to his strong city of Nineveh. Or, as it is in the margin, which see. And his princes shall be afraid of the ensign — Of the Lord’s ensign, which he hath lifted up against them. Or, as וחתו מנס, may be properly rendered, shall be struck with consternation at his flight. Saith the Lord, whose fire is in Zion — That is, either, 1st, whose fire is continually burning upon the altar in Zion; a sign that his presence and residence are there. Or, rather, 2d, who is, and will appear to be, in Zion like a fire, to defend his people, and to consume their enemies. Thus God promises that he would be, unto Jerusalem, a wall of fire round about, Zechariah 2:5. See also Zechariah 12:6.