Let them be confounded - Let them be ashamed. That is, Let them have that kind of shame and confusion which results from the fact that their plans have not been successful, or that they have been foiled and baffled in their schemes.
And troubled - Disturbed; put to confusion. Let them be troubled as men are who are unsuccessful in their projects.
Forever - As a people; as confederated nations; as united in such an unholy alliance. Let them never again be able thus to combine, or to form a compact for the destruction of thy people. This does not refer to them as individuals, but as nations. It is a prayer that they may be so discomfited now that they may see the wickedness and folly of all such efforts, and that they may never again form such a combination.
Yea, let them be put to shame - By utter failure in their schemes.
And perish - Not individually, but as combined - as an alliance. Let there be a complete end to such a confederacy, so that it shall never be seen again.

Let them - perish - That is, in their present attempts. Some have objected to the execrations in this Psalm, without due consideration. None of these execrations refer either to their souls or to their eternal state; but merely to their discomfiture on their present attempts. Suppose the continental powers should join together to subjugate Britain, and destroy the Protestant religion; is there a Christian in the land that would not be justified in meeting them with the same or similar execrations? On the knees of my soul would I offer every one of them to God against such invaders. Selah - A. C.

Let them be confounded and troubled for ever,.... As long as they are in this world, and to all eternity in another; a dreadful portion this:
yea, let them be put to shame, and perish; wholly and eternally, in soul and body, for evermore.

The aim of the wish is that they in the midst of their downfall may lay hold upon the mercy of Jahve as their only deliverance: first they must come to nought, and only by giving Jahve the glory will they not be utterly destroyed. Side by side with אתּה, v. 19a, is placed שׁמך as a second subject (cf. Psalm 44:3; Psalm 69:11). In view of Psalm 83:17 וידעוּ (as in Psalm 59:14) has not merely the sense of perceiving so far as the justice of the punishment is concerned; the knowledge which is unto salvation is not excluded. The end of the matter which the poet wishes to see brought about is this, that Jahve, that the God of revelation (שׁמך), may become the All-exalted One in the consciousness of the nations.