Ecclesiastes 2:17-21

So I hated life, because the work that is wrought under the sun was grievous unto me; for all is vanity and a striving after wind. And I hated all my labor wherein I labored under the sun, seeing that I must leave it unto the man that shall be after me. And who knoweth whether he will be a wise man or a fool? yet will he have rule over all my labor wherein I have labored, and wherein I have showed myself wise under the sun. This also is vanity. Therefore I turned about to cause my heart to despair concerning all the labor wherein I had labored under the sun. For there is a man whose labor is with wisdom, and with knowledge, and with skilfulness; yet to a man that hath not labored therein shall he leave it for his portion. This also is vanity and a great evil.