He increaseth the nations, and destroyeth them - He has entire control over them. The sources of prosperity are in his hand, and at his pleasure he can visit them with famine, pestilence, or war, and diminish their numbers and arrest their prosperity. Dr. Good renders this very improperly, "He letteth the nations grow licentious;" but the word שׂגא śâgâ' never has this sense. It means, to make great; to multiply; to increase.
And straiteneth them again - Margin, "leadeth in." So the word נחה nâchâh means. The idea is, that he increases a nation so that it spreads abroad beyond its usual limits, and then at his pleasure leads them back again, or confines them within the limits from where they had emigrated.

He increaseth the nations - Mr. Good translates, He letteth the nations grow licentious. Pride, fullness of bread, with extensive trade and commerce, produce luxury; and this is ever accompanied with profligacy of manners. When, then, the cup of this iniquity is full, God destroys the nation, by bringing or permitting to come against it a nation less pampered, more necessitous, and inured to toil.
He enlargeth the nations - Often permits a nation to acquire an accession of territory, and afterwards shuts them up within their ancient boundaries, and often contracts even those. All these things seem to occur as natural events, and the consequences of state intrigues, and such like causes; but when Divine inspiration comes to pronounce upon them, they are shown to be the consequence of God's acting in his judgment and mercy; for it is by him that kings reign; it is he who putteth down one and raiseth up another.

He (m) increaseth the nations, and destroyeth them: he enlargeth the nations, and straiteneth them [again].
(m) In this discourse of God's wonderful works, Job shows that whatever is done in this world both in the order and change of things, is by God's will and appointment, in which he declares that he thinks well of God, and is able to set forth his power in words as they that reasoned against him were.

He increaseth the nations, and destroyeth them,.... As he did before the flood, when the earth was tilled, and all over peopled with them, but at the flood he destroyed them at once. Sephorno interprets it of the seven nations in the land of Canaan, which were increased in it, and destroyed, to make way for the Israelites to inhabit it; and this has since been verified in other kingdoms, large and populous, and brought to destruction, particularly in the four monarchies, Babylonian, Persian, Grecian, and Roman, and will be in the antichristian states and nations of the world:
he enlargeth the nations, and straiteneth them again; or "stretcheth" or "spreadeth out the nations" (c), as he did all over the earth before the deluge, and then most remarkably straitened them, when they were reduced to so small a number as to be contained in a single ark: "or leads them" (d); that is, "governs them", as Mr. Broughton renders the word, rules and overrules them, as large as they are; or leads them into captivity, as some Jewish writers (e), as the Israelites; though they have been enlarged, and became numerous, as it was promised they should, yet have been led into captivity, first the ten tribes by the Assyrians, and then the two tribes by the Chaldeans; the Targum is, "he spreadeth out a net for the nations, and leadeth them", that is, into it, so that they are taken in it, see Ezekiel 12:13.
(c) "extendit", Tigurine version, Drusius, Mercerus; "expandit", Beza, Junius & Tremellus, Piscator, Schmidt; "expandens", Schultens. (d) "et ducit eas", Pagninus, Montanus, Mercerus, Cocceius, Schmidt. (e) Kimchi, Ben Melech, Bar Tzemach.

Isaiah 9:3; Psalm 107:38-39, which Psalm quotes this chapter elsewhere. (See on Job 12:21).
straiteneth--literally, "leadeth in," that is, "reduces."

Nations - What hitherto he said of princes, he now applies to nations, whom God does either increase or diminish as he pleases.