Ecclesiastes 2:17-26 (ESV)
17 So I hated life, because what is done under the sun was grievous to me, for all is vanity and a striving after wind.
The Vanity of Toil
18 I hated all my toil in which I toil under the sun, seeing that I must leave it to the man who will come after me, 19 and who knows whether he will be wise or a fool? Yet he will be master of all for which I toiled and used my wisdom under the sun. This also is vanity. 20 So I turned about and gave my heart up to despair over all the toil of my labors under the sun, 21 because sometimes a person who has toiled with wisdom and knowledge and skill must leave everything to be enjoyed by someone who did not toil for it. This also is vanity and a great evil. 22 What has a man from all the toil and striving of heart with which he toils beneath the sun? 23 For all his days are full of sorrow, and his work is a vexation. Even in the night his heart does not rest. This also is vanity.
24 There is nothing better for a person than that he should eat and drink and find enjoyment  in his toil. This also, I saw, is from the hand of God, 25 for apart from him  who can eat or who can have enjoyment? 26 For to the one who pleases him God has given wisdom and knowledge and joy, but to the sinner he has given the business of gathering and collecting, only to give to one who pleases God. This also is vanity and a striving after wind.