The prince that wanteth understanding - A weak prince will generally have wicked ministers, for his weakness prevents him from making a proper choice; and he is apt to prefer them who flatter him, and minister most to his pleasures. The quantum of the king's intellect may be always appreciated by the mildness or oppressiveness of his government. He who plunges his people into expensive wars, to support which they are burdened with taxes, is a prince without understanding. He does not know his own interest, and does not regard that of his people. But these things, though general truths, apply more particularly to those despotic governments which prevail in Asiatic countries.

The prince that wanteth understanding is also a great oppressor,.... Or, "much in oppressions" (o); he multiplies them, and abounds in them; he distresses his subjects in a variety of ways and methods he uses to extort money from them by which he shows his want of understanding: he is a wise prince that uses gentle methods, and gains the affections of his people, and who cheerfully supports his crown and government with honour and glory; but he is a foolish prince that uses them with rigour. It may be rendered, "and a prince that wanteth understanding, and is much", or "abounds, in oppressions"; in laying heavy burdens and taxes on his people, in an arbitrary manner; "shall shorten, and not prolong his days" (p), as it may be supplied from the next clause; either his subjects will rise up against him, and dethrone him, and destroy him; or God, in mercy to them, and in judgment to him, will remove him by death;
but he that hateth covetousness shall prolong his days; to hate covetousness is a good qualification of a civil magistrate, prince, or ruler, Exodus 18:21. This sin is the cause of a wicked prince oppressing his subjects; but where it is hated, which is seen by moderation in government, and easing of the people as much as possible; such a prince, as he has the hearts of his subjects, is well pleasing to God, by whom he reigns; and such an one, through the prayers of the people for him, and the goodness of God unto him, lives long, and reigns prosperously; and dies, as David, in a good old age, full of days, riches, and honour.
(o) "multus oppressionibus", Montanus, Junius & Tremeilius, Piscator, Mercerus, Baynus, Michaelis, Schultens. (p) So Junius & Tremellius, Piscator, Gejerus, and some Jewish writers in Vatablus.

Oppressors want understanding; they do not consult their own honour, ease, and safety.

The prince . . . understanding--that is, He does not perceive that oppression jeopards his success. Covetousness often produces oppression, hence the contrast.

Another proverb of the king:
O prince devoid of understanding and rich in oppression!
He that hateth unrighteous gain continueth long.
The old interpreters from the lxx interpret מעשׁקּות רבו as pred. (as also Fleischer: princeps qui intelligentiae habet parum idem oppressionis exercet multum); but why did not the author use the word הוּא or והוּא instead of this ambiguous inconvenient ו? Hitzig regards the first term as a nominative absolute, which does not assume a suffix in the second line. But examples such as 27a, Proverbs 27:7, are altogether of a different sort; there occurs a reference that is in reality latent, and only finds not expression; the clause following the nominative is related to it as its natural predicate, but here 15b is an independent clause standing outside of any syntactical relation to 15a. Heidenheim has acknowledged that here there lies before us a proverb not in the form of a mere declaration, but of a warning address, and thus also it is understood by Ewald, Bertheau, Elster, and Zckler. The accentuation seems to proceed on the same supposition. It is the only passage in the Book of Proverbs where נגיד, of the supreme ruler of the people, and where the plur. תּבוּנות, occur; it is not therefore at all strange if the proverb also has something strange in its formation. Often enough, proverbs are in the form of an address to a son, and generally to their reader; why not also one at least to the king? It is a proverb as when I say: Oh thou reckless, merry fellow! he who laughs much will sometimes weep long. Thus here the address is directed to the prince who is devoid of all wisdom and intelligence, which are necessary for a prince; but on this account the more earnest in exhortation to say to him that only one who hates defrauding the people attains an old age; thus that a prince who plunders the people wantonly shortens his life as a man, and his position as a ruler (cf. שׁניהם, Proverbs 24:22). The Kerı̂ שׂנא has the tone thrown back on the penult., as the Chethı̂b שׂנאי would also have it, cf. למצאי, Proverbs 8:9. The relation of a plur. subj. to a sing. pred. is as at Proverbs 27:16. Regarding בּצע, vid., under Proverbs 1:19. A confirmation of this proverb directing itself to princes if found in Jeremiah 22:13-19, the woe pronounced upon Jehoiakim. And a glance at the woe pronounced in Habakkuk 2:12, shows how easily Proverbs 28:17 presents itself in connection.

Oppressor - The tyranny of a prince, is a manifest sign of folly. Prolong - By God's favour, the peace and satisfaction of his own mind, and the hearty love of his people.