Ecclesiastes 2:15,21
Then said I in my heart, As it happens to the fool, so it happens even to me; and why was I then more wise? Then I said in my heart, that this also is vanity.
Nave's Topical Index—AKJV

1 Corinthians 3:20
And again, The Lord knows the thoughts of the wise, that they are vain.
Nave's Topical Index—AKJV