Trust not in princes This admonition is appropriately inserted, for one means by which men blind themselves is that of involving their minds through a number of inventions, and being thus prevented from engaging in the praises of God. That God may have the whole praise due to him, David exposes and overthrows those false stays on which we would otherwise be too much disposed to trust. His meaning is, that we should withdraw ourselves from man in general, but he names princes, from whom more is to be feared than common men. For what promise could poor people hold out, or such as need the help of others? The great and wealthy, again, have a dangerous attraction through the splendor attaching to them, suggesting to us the step of taking shelter under their patronage. As the simple are fascinated by looking to their grandeur, he adds, that the most powerful of the world's princes is but a son of man This should be enough to rebuke our folly in worshipping them as a kind of demigods, as Isaiah says, (Isaiah 31:3,) "The Egyptian is man, and not God; flesh, and not spirit." Although princes then are furnished with power, money, troops of men, and other resources, David reminds us, that it is wrong to place our trust in frail mortal man, and vain to seek safety where it cannot be found. This he explains more fully in the verse, which follows, where he tells us how short and fleeting the life of man is. Though God throw loose the reins, and suffer princes even to invade heaven in the wildest enterprises, the passing of the spirit, like a breath, suddenly overthrows all their counsels and plans. The body being the dwelling-place of the soul, what is here said may very well be so understood; for at death God recalls the spirit. We may understand it more simply, however, of the vital breath; and this will answer better with the context -- that as soon as man has ceased to breathe, his corpse is subject to putrefaction. It follows, that those who put their trust in men, depend upon a fleeting breath. When he says that in that day all his thoughts perish, or flow away, perhaps under this expression he censures the madness of princes in setting no bounds to their hopes and desires, and scaling the very heavens in their ambition, like the insane Alexander of Macedon, who, upon hearing that there were other worlds, wept that he had not yet conquered one, although soon after the funeral urn sufficed him. Observation itself proves that the schemes of princes are deep and complicated. That we may not fall, therefore, into the error of connecting our hopes with them, David says that the life of princes also passes away swiftly and in a moment, and that with it all their plans vanish.

Put not your trust in princes - Rely on God rather than on man, however exalted he may be. There is a work of protection and salvation which no man, however exalted he may be, can perform for you; a work which God alone, who is the Maker of all things, and who never dies, can accomplish. See the notes at Psalm 118:8-9. Compare also the notes at Isaiah 2:22 : "Cease ye from man, whose breath is in his nostrils, for wherein is he to be accounted of?"
Nor in the son of man - Any son of man; any human being, no matter what his rank or power. The phrase is often used to denote man. See the notes at Psalm 8:4. The appellation "Son of man" was often applied by the Saviour to himself to express emphatically the idea that he was a man - that he had a human nature; that he was identified with the race; that he was a brother, a fellow-sufferer, a friend of man: that he was not a cold and abstract being so exalted that he could not feel or weep over the sins and woes of a fallen and suffering world. The language here, however, it is scarcely necessary to say, does not refer to him. It is right to put our trust in him; we have no other trust.
In whom there is no help - Margin, salvation. So the Hebrew. The idea is, that man cannot save us. He cannot save himself; he cannot save others.

Put not your trust in princes - This may refer, as has been stated above, to Cyrus, who had revoked his edict for the rebuilding of Jerusalem. Perhaps they had begun to suppose that they were about to owe their deliverance to the Persian king. God permitted this change in the disposition of the king, to teach them the vanity of confidence in men, and the necessity of trusting in himself.

Put not your trust in (b) princes, [nor] in the son of man, in whom [there is] no help.
(b) That God may have the whole praise: in which he forbids all vain confidence showing that by nature we are more inclined to put our trust in creatures, than in God the Creator.

Put not your trust in princes,.... Not in foreign princes, in alliances and confederacies with them; nor in any at home. David did not desire his people to put their trust in him, nor in his nobles and courtiers; but in the Lord Christ, who, as he is the object of praise, is also the proper object of trust. Princes, though ever so liberal and bountiful, as their name signifies, and therefore called benefactors, Luke 22:25 or ever so mighty and powerful, wise and prudent, yet are not to be depended upon; they are changeable, fickle, and inconstant; and oftentimes not faithful to their word, but fallacious and deceitful; "men of high degree are a lie", Psalm 62:9; wherefore it is better to trust in the Lord Jehovah, in whom is everlasting strength; who gives all things richly to enjoy; who is unchangeable, and ever abides faithful; see Psalm 118:8;
nor in the son of man, in whom there is no help; or "salvation" (m): not in any mere man born of a woman; not in Abraham, the father of the faithful, of whom the Jews boasted, as the Midrash; nor in Moses, as Arama; nor in Cyrus, as R. Obadiah; no, nor in David himself, nor in any of the princes; for how great soever they look, or in whatsoever honour and esteem they may be, they are but sons of men; are frail mortal men, and die like men, though they may be called gods, as they are by office: but no man or son of man, let him be what he will, is to be trusted in; there is a curse on him that does it, Jeremiah 17:5. There is indeed a Son of man that is to be trusted in, the Lord Jesus Christ; but then he is God as well as man, the true God, the great God, God over all, blessed for ever; were he not, he would not be the proper object of trust, for there is no "help" or "salvation" in a mere creature; even kings and princes cannot help and save themselves oftentimes, and much less their people; their salvation is of God, and not from themselves, or from their armies, Psalm 33:16. There is help in Christ, on whom it is laid, and where it is found; there is salvation in him, but in no other; he is the author and giver of it, and therefore he, and not another, is to be trusted in.
(m) "salus", V. L. Pagninus, Montanus, Junius & Tremellius, Piscator, &c.