'Toiled' in the Bible

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.

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).

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?