Ecclesiastes 2:11, 15, 17, 19, 21, 23, 26

Then I considered all which my hands had done and labored to do, and behold, all was vanity and chasing after the wind and there was no profit (nothing of lasting value) under the sun. [Matt 16:26]

Then I said to myself, “As it happens to the fool, so death will also happen to me. What use is it then for me to be extremely wise?” Then I said in my heart, “This too is vanity (meaningless).”

So I hated life, for the work which had been done under the sun caused me only great sorrow; because all is futility and chasing after the wind.

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 all his days his work is painful and sorrowful; even at night his mind does not rest. This too is vanity (worthless).

For to the person who pleases Him God gives wisdom, knowledge, and joy; but to the sinner He gives the work of gathering and collecting so that he may give to one who pleases God. This too is vanity and chasing after the wind.