Ecclesiastes 2:26
For God gives to a man that is good in his sight wisdom, and knowledge, and joy: but to the sinner he gives travail, to gather and to heap up, that he may give to him that is good before God. This also is vanity and vexation of spirit.
Nave's Topical Index—AKJV

Ecclesiastes 4:8
There is one alone, and there is not a second; yes, he has neither child nor brother: yet is there no end of all his labor; neither is his eye satisfied with riches; neither said he, For whom do I labor, and bereave my soul of good? This is also vanity, yes, it is a sore travail.
Nave's Topical Index—AKJV