There is a vanity which is done upon the earth; that there be just men, unto whom it happeneth according to the work of the wicked; again, there be wicked men, to whom it happeneth according to the work of the righteous: I said that this also is vanity.
There be just (men) ... An objection is here started (entertained by Solomon in his apostasy), as in Ecclesiastes 3:16; Ecclesiastes 7:15, to the truth of retributive justice, from the fact of the just and the wicked not now receiving always according to their respective deserts; a cavil which would seem the more weighty to men living under the Mosaic covenant of temporal sanctions. The objector adds, as Solomon had said, that the worldling's pursuits are "vanity" (Ecclesiastes 8:10), "I say (not 'said') this also is vanity. Then I commend mirth." etc. (Holden.) Ecclesiastes 8:14-15, however, ought rather to be explained as teaching a cheerful, thankful use of God's gifts "under the sun" - i:e., not making them the chief good, as sensualists do, which Ecclesiastes 2:2; Ecclesiastes 7:2, forbid; but in "the fear of God," as Ecclesiastes 3:12; Ecclesiastes 5:18; Ecclesiastes 7:18; Ecclesiastes 9:7, opposed to the abstinence of the self-righteous ascetic (Ecclesiastes 7:16), and of the miser (Ecclesiastes 5:17).
This also is vanity. God has intended such vanity or imperfection and misery to inhere in things of this fallen earth, in order that the godly may be disciplined to walk by faith, serving God in spite of many trials, not for the sake of earthly reward, as Satan accused Job of (Job 1:9), but for love to Him who is their final reward. Even they have much of sin, and must therefore take their share of the general misery of this vain life, with this difference, as compared with the ungodly, that even trials work together for their final good.