Ecclesiastes 2:19 in the World English Bible
Who knows whether he will be a wise man or a fool? Yet he will have rule over all of my labor in which I have labored, and in which I have shown myself wise under the sun. This also is vanity.
Context
18 Yea, I hated all my labour which I had taken under the sun: because I should leave it unto the man that shall be after me.
19 And who knoweth whether he shall be a wise man or a fool? yet shall he have rule over all my labour wherein I have laboured, and wherein I have shewed myself wise under the sun. This is also vanity.
20 Therefore I went about to cause my heart to despair of all the labour which I took under the sun.