Ecclesiastes 4:4; Ecclesiastes 4:7-8

4 Then I saw that all toil and all skill in work come from a man’s envy of his neighbor. This also is vanity and a striving after wind.

7 Again, I saw vanity under the sun:

8 one person who has no other, either son or brother, yet there is no end to all his toil, and his eyes are never satisfied with riches, so that he never asks, “For whom am I toiling and depriving myself of pleasure? ” This also is vanity and an unhappy business.