Ecclesiastes 2:20-23

²⁰Therefore I turned to give up my heart to despair in regard to all the labor with which I had wearied myself under the sun.

²¹For there is a man whose labor has been with wisdom and knowledge and skill; yet to a man who hath not labored for it must he leave it as his portion. This also is vanity and a great evil.

²²For what hath man of all his labor, and the striving of his spirit, with which he wearieth himself under the sun?

²³For all his days are grief, and his occupation trouble; even in the night his heart taketh no rest. This also is vanity.