Ecclesiastes 2:20-23

Therefore I turned my heart and despaired of all the labor in which I had toiled under the sun. For there is a man whose labor is with wisdom, knowledge, and skill; yet he must leave his heritage to a man who has not labored for it. This also is vanity and a great evil. For what has man for all his labor, and for the striving of his heart with which he has toiled under the sun? For all his days are sorrowful, and his work burdensome; even in the night his heart takes no rest. This also is vanity.