Ecclesiastes 4:4; Ecclesiastes 4:7-8

4 I realized the reason people work hard and try to succeed: They are jealous of each other. This, too, is useless, like chasing the wind.

7 Again I saw something here on earth that was useless:

8 I saw a man who had no family, no son or brother. He always worked hard but was never satisfied with what he had. He never asked himself, "For whom am I working so hard? Why don't I let myself enjoy life?" This also is very sad and useless.