Albert Barnes Commentary Psalms 92:6

"A brutish man knoweth not; Neither doth a fool understand this:" — Psalms 92:6 (ASV)

A brutish man does not know—A man who is stupid and like the beasts or brutes; that is, a man whose tastes and propensities are like the brutes, or who does not seem to act as if endowed with a rational nature. The idea evidently is that there are many such people, and it is no wonder that they have no exalted idea of the greatness of God. As a matter of fact, there are many in human form—many made in the image of God—who seem to have no more notion of God, and who see no more wisdom and goodness in His works, than the horse or the ox. .

Neither does a fool understand this—A fool, in the sense that he has been made foolish and stupid by sin; that he does not worship and honor God. He has no right understanding regarding the Maker and the Governor of the universe.