And as the small dust. [1] I shall first state the opinions of others, and afterwards I shall bring forward what I consider to be more probable. Almost all the commentators think that this expression denotes the enemies of the Jews; for they consider "foreigners" to mean "enemies," and allege that the multitude of those who shall oppress the Jews shall be "like dust;" that is, it shall be innumerable. But when I examine closely the whole passage, I am more disposed to adopt a contrary opinion. I think that the Prophet speaks contemptuously of the garrisons on which the Jews foolishly relied, for they had in their pay foreign soldiers who were strong men. The multitude of the mighty ones. Such is the interpretation which I give to rytsym (gnaritzim), which is also its literal meaning; and I see no reason why some of the Jews should suppose it to mean ungodly or wicked persons. Since, therefore, the Jews brought various garrisons from a distance, they thought that they were well defended, and dreaded no danger. The Prophet threatens that their subsidiary troops, though they were a vast multitude, shall in vain create a disturbance, for they shall be like "dust" or "chaff," that is, useless refuse, for they shall produce no effect. [2] Hence we ought to infer, that our wealth and resources, however great they are, shall be reduced to nothing, as soon as the Lord shall determine to deal with us as he has a right to do. The assistance of men lasts indeed for a time; but when the Lord shall lift up his hand in earnest, their strength must crumble down, and they must become like chaff. And it shall be in a moment suddenly. Some explain the concluding clause of this verse to mean, that the noise of the enemies' attack shall spring up suddenly, and, as it were, in a moment. But I consider vhych, (vEhayah,) and it shall be, to relate to the time of duration, which he declares will be momentary; that is, those military aids shall not last long, but shall quickly vanish away. [3] In vain do men boast of them, for God is their enemy.

Footnotes

1 - The Septuagint renders it, kai estai hos koniortos apo trochou ho ploutos ton asebon, "and as the small dust from the wheel shall be the multitude of the wicked." Here it is necessary to attend to the distinction between trochos and trochos -- Ed

2 - The military forces of Sennacherib, which shall be fuel for the fire, and shall be reduced to powder." -- Jarchi

3 - "They shall be destroyed by the pestilential blast Simoom, whose effects are instantaneous. Thevenot describes this wind with all the circumstances here enumerated, with thunder and lightning, insufferable heat, and a whirlwind of sand. By such an angel of Jehovah,' as it is called below, (Isaiah 37:36,) was the host of Assyria destroyed." -- Stock

Moreover - These verses Isaiah 29:5, Isaiah 29:7-8 contain a beautiful description of the destruction of the army of Sennacherib. Though they had laid the plan of a regular siege; though the city, in itself, would not be able to hold out against them, and all was alarm and conscious imbecility within; yet in an instant the siege would be raised, and the advancing hosts of the Assyrians would all be gone.
The multitude of thy strangers - The multitude of the strangers that shall besiege thee; called 'thy strangers,' because they besieged, or oppressed thee. The word 'strangers' here, as elsewhere, means "foreigners" (see the note at Isaiah 1:7; compare Isaiah 2:6; Isaiah 5:17; Isaiah 14:1; Isaiah 25:2, Isaiah 25:5; Isaiah 29:5; Isaiah 60:10).
Shall be like small dust - Light, fine dust that is easily dissipated by the wind.
Of the terrible ones - Of the invading, besieging army, that is so much the object of dread.
As chaff that passeth away - (see the note at Isaiah 17:13). This image of chaff driven before the wind, to denote the sudden and entire discomfiture of enemies, is common in the Scriptures (see Job 21:18; Psalm 1:4; Psalm 35:5; Hosea 13:13).
Yea, it shall be at an instant suddenly - The forces of Sennacherib were destroyed in a single night by the angel of the Lord (Isaiah 37:36; the note at Isaiah 10:12, Isaiah 10:28-34, note), and the siege of Jerusalem was of course immediately raised.

The multitude of thy strangers "The multitude of the proud" - For זריך zarayich, thy strangers, read זדים zedim, the proud, according to the Septuagint; parallel to and synonymous with עריצים aritsim, the terrible, in the next line: the ר resh was at first ד daleth in a MS. See note on Isaiah 25:2.
The fifth, sixth, and seventh verses contain an admirable description of the destruction of Sennacherib's army, with a beautiful variety of the most expressive and sublime images: perhaps more adapted to show the greatness, the suddenness, and horror of the event, than the means and manner by which it was effected. Compare Isaiah 30:30-33.

Moreover the multitude of thy (e) strangers shall be like small dust, and the multitude of the terrible ones [shall be] as chaff that passeth away: yea, it shall be at an instant suddenly.
(e) Your hired soldiers in whom you trusted, will be destroyed as dust or chaff in a whirlwind.

Moreover, the multitude of thy strangers shall be like small dust,.... Or "of those that fan thee" (q), as the Vulgate Latin Version; and so the Targum,
"of those that scatter thee;''
or of thine enemies, as others; meaning the Romans, who were a strange people to them, who got the dominion over them, and scattered them abroad in the world: and the simile of "small dust", to which they are compared, is not used to express the weakness of them, but the greatness of their number, which was not to be counted, any more than the dust of the earth; see Numbers 23:10,
and the multitude of the terrible ones shall be as chaff that passeth away; designing the same numerous army of the Romans as before, who were terrible to the Jews: nor does this metaphor signify any imbecility in them, and much less the ruin of them, but their swiftness in executing the judgments of God upon his people, who moved as quick as chaff, or any such light thing, before a mighty wind:
yea, it shall be at an instant suddenly; either the numerous army should be suddenly before Jerusalem, or the destruction of that city should be as it were in a moment; and though the siege of it lasted long, yet the last sack and ruin of it was suddenly, and in so short a time, that it might be said to be in an instant, in a moment, as it were. The Jewish writers interpret this of the sudden destruction of Sennacherib's army by the angel, 2-Kings 19:35 but the next words show that the destruction of Jerusalem is meant.
(q) "ventilantium te", V. L. "dispergentium te", Vatablus, so Targum; "hostium tuorum", Pagninus, Cocceius.

Moreover--rather, "Yet"; yet in this extremity help shall come, and the enemy be scattered.
strangers--foreign enemies, invaders (Isaiah 25:2).
it shall be--namely, the destruction of the enemy.
at an instant--in a moment (Isaiah 30:23).

Thus far does the unfolding of the hoi reach. Now follows an unfolding of the words of promise, which stand at the end of Isaiah 29:1 : "And it proves itself to me as Ariel." Isaiah 29:5-8 : "And the multitude of thy foes will become like finely powdered dust, and the multitude of the tyrants like chaff flying away; and it will take place suddenly, very suddenly. From Jehovah of hosts there comes a visitation with crash of thunder and earthquake and great noise, whirlwind and tempest, and the blazing up of devouring fire. And the multitude of all the nations that gather together against Ariel, and all those who storm and distress Ariel and her stronghold, will be like a vision of the night in a dream. And it is just as a hungry man dreams, and behold he eats; and when he wakes up his soul is empty: and just as a thirsty man dreams, and behold he drinks; and when he wakes up, behold, he is faint, and his soul is parched with thirst: so will it be to the multitude of the nations which gather together against the mountain of Zion." The hostile army, described four times as hâmōn, a groaning multitude, is utterly annihilated through the terrible co-operation of the forces of nature which are let loose upon them (Isaiah 30:30, cf., Isaiah 17:13). "There comes a visitation:" tippâqēd might refer to Jerusalem in the sense of "it will be visited" in mercy, viz., by Jehovah acting thus upon its enemies. But it is better to take it in a neuter sense: "punishment is inflicted." The simile of the dream is applied in two different ways: (1.) They will dissolve into nothing, as if they had only the same apparent existence as a vision in a dream. (2.) Their plan for taking Jerusalem will be put to shame, and as utterly brought to nought as the eating or drinking of a dreamer, which turns out to be a delusion as soon as he awakes. Just as the prophet emphatically combines two substantives from the same verbal root in Isaiah 29:1, and two adverbs from the same verb in Isaiah 29:5; so does he place צבא and צבה together in Isaiah 29:7, the former with על relating to the crowding of an army for the purpose of a siege, the latter with an objective suffix (compare Psalm 53:6) to the attack made by a crowded army. The metsōdâh of Ariel (i.e., the watch-tower, specula, from tsūd, to spy)
(Note: In Arabic, also, masâd signifies a lofty hill or mountain-top, from a secondary form of tsud; and massara, to lay the foundations of a fortified city (‛ı̄r mâtsōr, Psalm 31:22), from tsūr.))
is the mountain of Zion mentioned afterwards in Isaiah 29:8. כּאשׁר, as if; comp. Zac 10:6; Job 10:19. אוכל והנּה without הוּא; the personal pronoun is frequently omitted, not only in the leading participial clause, as in this instance (compare Isaiah 26:3; Isaiah 40:19; Psalm 22:29; Job 25:2; and Khler on Zac 9:12), but also with a minor participial clause, as in Psalm 7:10; Psalm 55:20, and Habakkuk 2:10. The hungering and thirsting of the waking man are attributed to his nephesh (soul: cf., Isaiah 32:6; Isaiah 5:14; Proverbs 6:30), just because the soul is the cause of the physical life, and without it the action of the senses would be followed by no sensation or experience whatever. The hungry stomach is simply the object of feeling, and everything sensitive in the bodily organism is merely the medium of sensation or feeling; that which really feels is the soul. The soul no sooner passes out of the dreaming state into a waking condition, than it feels that its desires are as unsatisfied as ever. Just like such a dream will the army of the enemy, and that victory of which it is so certain before the battle is fought, fade away into nothing.

Strangers - Whom thou hast hired to assist thee, as indeed they did, when the Chaldeans came against them. Terrible ones - Thy great commanders, and stout soldiers. It - This destruction of thy strangers, and terrible ones shall come to pass.