Ecclesiastes 2:22
For what has man of all his labor, and of the vexation of his heart, wherein he has labored under the sun?
Torrey's Topical Textbook—AKJV

Ecclesiastes 6:12
For who knows what is good for man in this life, all the days of his vain life which he spends as a shadow? for who can tell a man what shall be after him under the sun?
Torrey's Topical Textbook—AKJV