This is added as the reason of the judgments mentioned in the foregoing verse, God doth not afflict nor destroy either princes or people unjustly, no, nor out of his mere pleasure and absolute sovereignty, (to which Job seemed to impute his calamities,) but for their sins, which God sees exactly, although they use all possible arts and tricks to hide them from him. Therefore no man hath cause to complain of God, but of himself, for all that he may suffer in the world.
Related Commentaries of Job 34:21
Job 34:21
21 For his eyes are upon the ways of man, and he seeth all his goings.