Ecclesiastes 8:14-17

14 There is a vanity that takes place on earth, that there are righteous people to whom it happens according to the deeds of the wicked, and there are wicked people to whom it happens according to the deeds of the righteous. I said that this also is vanity. 15 And I commend joy, for man has nothing better under the sun but to eat and drink and be joyful, for this will go with him in his toil through the days of his life that God has given him under the sun.

16 When I applied my heart to know wisdom, and to see the business that is done on earth, how neither day nor night do one's eyes see sleep, 17 then I saw all the work of God, that man cannot find out the work that is done under the sun. However much man may toil in seeking, he will not find it out. Even though a wise man claims to know, he cannot find it out.