And the hail. We have already said that the prophets are accustomed frequently to describe under figures the reign of Christ; for they borrow their metaphors from an earthly kingdom, because our ignorance would make it almost impossible for us to comprehend, in any other way, the unspeakable treasure of blessings. The meaning is, "The Lord will remove from his people distresses and annoyances, and will make them fall on others;" because here we are liable to various storms and tempests, and must endure rain, hail, showers, winds, and tempests. He says that God, by his wonderful providence, will prevent all distresses from doing any injury to believers, because he will drive their violence in another direction. By forests he means unfrequented and desert places, where there are no crowds of men. Hence we learn that, when we are under the guardianship of Christ, we are protected from inconveniences and dangers, but that, at the same time, various storms and tempests are ready to burst on our heads. But the Lord is our deliverer, who turns away in another direction the evils that are approaching, or rescues us when we are in danger. And the city shall be situated to a low place. [1] In order to confirm what he had said about peace, he says, that "cities," which shall be situated on level ground, will be out of danger; for at that time it was customary to build on high and elevated places, that the access to them might be more difficult. "Such," says he, "will be God's protection of his people, that they will not need the ordinary fortifications, because the city may be safely set down in valleys; and even although it be liable to the attacks of enemies, it will sustain no inconvenience, for the hand of the Lord will protect it." We must not therefore seek safety by relying on our defences, lest we be immediately driven from our nest; but since our heavenly Father deigns to provide for our safety, let us be satisfied with having him for our protector and guardian. [2]

Footnotes

1 - "And the city shall be low in a low place;" or, "And the city shall be utterly abased." -- Eng. Ver.

2 - "Some by the Forest understand Nineveh, some Babylon, some Jerusalem, and some the Assyrian army; but Gataker, and Vatablus before him, think the words may be rendered, he shall hail with hail on the forest, and cities shall be built in low places; as if he had said, God shall preserve the fruits of the earth from the injuries of unseasonable weather, and, when he sends a storm of hail, cause it to fall on the woods and deserts; and he shall give them so great security, that for the future they shall build their cities in low grounds, to shew that they are under no apprehension of being overrun any more by an enemy." -- White

When it shall hail - Hebrew, ברדת ברד bârad beredeth - 'And it shall hail in coming down. There is a paranomasia in the original here, which cannot be expressed in a translation - a figure of speech, which, as we have seen, is common in Isaiah. 'Hail' is an image of divine vengeance or punishment; and the reference here is, doubtless, to the storms of indignation that would come on the enemies of the Jews, particularly on the Assyrians (see the notes at Isaiah 30:30).
Coming down on the forest - Coming down on the army of the Assyrian, which is here called 'a forest.' The same term 'forest' is given to the army of the Assyrians in Isaiah 10:18-19, Isaiah 10:33-34. The sense is, that the divine judgment would come down on that army with as much severity as a storm of hail descends on a forest - stripping the leaves from the trees, destroying its beauty, and laying it waste.
And the city - According to Gesenius, this is Nineveh, the capital of the Assyrian empire. According to Rosenmuller, Grotius, and others, it is Babylon. Hensler supposes that it is Jerusalem, and that the sense is, that as a city that is situated in a valley is safe when the storm and tempest sweep over the hills, so would it be to Jerusalem when the storm of wrath should sweep away the army of the Assyrian. But the connection evidently requires us to understand it of the capital of the enemy; though whether it be Nineveh or Babylon perhaps cannot be determined.
Shall be low in a low place - Margin, 'Utterly abased.' Hebrew, 'In humility shall be humbled.' The sense is, shall be completely prostrate. Those who refer this to Jerusalem suppose it refers to the time when God should humble it by bringing the enemy so near, and exciting so much consternation and alarm. Those who refer it to Babylon suppose it relates to its destruction. If referred to Nineveh, it must mean when the pride of the capital of the Assyrian empire should be iratabled by the complete overthrow of their army, and the annihilation of their hopes. The connection seems to require us to adopt this latter interpretation. The whole verse is very obscure; but perhaps the above will express its general sense.

The city shalt be low all a low place. "The city shall be laid level with the plain" - For ובשפלה ubashephelah, the Syriac reads וכשפלה ukeshephelah. The city - probably Nineveh or Babylon: but this verse is very obscure. Saltus; Assyriorum regnum: civitas; magnifica Assyriorum castra. Ephrem Syr. ire loc. For וברד ubarad, a MS. has וירד vaiyered; and so conjectured Abp. Secker, referring to Zac 11:2.

When it shall hail, coming down on the forest; and the (m) city shall be low in a low place.
(m) They will not need to build it in high places for fear of the enemy: for God will defend it, and turn away the storms from hurting their conveniences.

When it shall hail, coming down on the forest,.... The people of God will be peaceable and quiet, safe and secure, when the judgments of God, signified by a "hail" storm, shall come upon antichrist, and the antichristian states, intended by the "forest", both for their numbers, and for their barrenness and unfruitfulness; see Revelation 16:21 and as so it sometimes is, by the disposition of divine Providence, that a storm of hail falls not upon fields and gardens, and the fruits of the earth, but upon forests and desert lands; and as the plague of hail fell upon the Egyptians, and not upon the Israelites in Goshen, to which some think the allusion is here; so will it be when God comes to take vengeance on the enemies of his people:
and the city shall be low in a low place: meaning not the city of Jerusalem, surrounded with mountains, built under hills, and so under the wind, and not exposed to the fury of a storm; but rather Babylon, built in a plain, in a low plain, and yet should be brought lower still; mystical Babylon is here meant, the city of Rome, that should "in humiliation be humbled", as the words may be rendered, that is, brought very low, exceeding low; see Isaiah 26:5 and which, at the time of the great hail, will be divided into three parts, and the cities of the nations shall fall, and Babylon be had in remembrance by the Lord to destroy it, Revelation 16:19.

Literally, "But it shall hail with coming down of the forest, and in lowness shall the city (Nineveh) be brought low; that is, humbled." The "hail" is Jehovah's wrathful visitation (Isaiah 30:30; Isaiah 28:2, Isaiah 28:17). The "forest" is the Assyrian host, dense as the trees of a forest (Isaiah 10:18-19, Isaiah 10:33-34; Zac 11:2).

It shall hail - As my blessings shall be poured down upon my people, who, from a wilderness, are turned into a fruitful field, so my judgments (which are signified by hail, Isaiah 28:2, Isaiah 28:17, and elsewhere) shall fall upon them, who were a fruitful field, but are turned into a forest, upon the unbelieving and rebellious Jews. The city - Jerusalem, which, though now it was the seat of God's worship and people, yet he foresaw, would be the great enemy of the Messiah. Low - Hebrews. shall be humbled with humiliation: shall be greatly humbled, or brought very low.