Deuteronomy 32:29

O that they were wise
These are not the words of God, and so no instances of mere velleities, and unsuccessful wishes in him, and as arguing a power in man to make himself wise if he would; but of Moses, under a spirit of prophecy, foreseeing the ignorance and stupidity of the above persons; or as representing a true believer in Christ, in the times in which such men should live; for the person speaking is one that had faith in Christ, the rock of salvation, and built upon him alone for it; and who had enemies on that account, as appears from ( Deuteronomy 32:31-33 ) : and these words are spoken not of the Jews, with whom this song has no more concern, unless it be in what respects, their conversion in the latter day; but of false Christians, Pelagians, Arians whose language and character are expressed in ( Deuteronomy 32:28 Deuteronomy 32:29 ) : and contain a pathetic wish that they might have wisdom to see their follies, errors, and mistakes, and renounce them: or, "if they were wise" ^F11; as they are not, and their tenets show it:

[that] they would understand this;
namely what follows:

[that] they would consider their latter end;
either the latter end of the Jews; had they wisdom, they would understand and observe that the displeasure of God against them, and his destruction of them, was for their lightly esteeming the rock of salvation, as Arians do; and for setting up their own righteousness, in opposition to the righteousness of Christ, as do Pelagians and Arminians; and were they wise, they would be hereby cautioned against such notions; and though imbibed by them, would relinquish them; as they may justly fear some such like end will be theirs: for if God does not give them repentance to the acknowledging of the truth their end must be miserable; since the errors they embrace and profess are what the apostle calls "damnable heresies"; who, denying the Lord that bought them, bring on themselves swift destruction; and whose judgment, he says, lingers not, and their damnation slumbers not, ( 2 Peter 2:1 2 Peter 2:3 ) .