Ecclesiastes 2:18-22

So I hated all the fruit (gain) of my labor for which I had labored under the sun, because I must leave it to the man who will succeed me. [Ps 49:10] And who knows whether he will be a wise man or a fool? Yet he will have control over all the fruit of my labor for which I have labored by acting wisely under the sun. This too is vanity (futility, self-conceit). So I turned aside and let my heart despair over all the fruit of my labor for which I had labored under the sun. For there is a man who has labored with wisdom and knowledge and skill, yet gives his legacy to one who has not labored for it. This too is vanity and a great evil. For what does a man get from all his labor and from the striving and sorrow of his heart with which he labors under the sun?