Ecclesiastes 2:20-23

²⁰Therefore I went about to cause my heart to despair of all the labour which I took under the sun.

²¹For there is a man whose labour is in wisdom, and in knowledge, and in equity; yet to a man that hath not laboured therein shall he leave it for his portion. This also is vanity and a great evil.

²²For what hath man of all his labour, and of the vexation of his heart, wherein he hath laboured under the sun?

²³For all his days are sorrows, and his travail grief; yea, his heart taketh not rest in the night. This is also vanity.