Verses with the word vanity in the New Testament (3 verses):

Romans 8:20
For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,

Ephesians 4:17
This I say therefore, and testify in the Lord, that ye henceforth walk not as other Gentiles walk, in the vanity of their mind,

2 Peter 2:18
For when they speak great swelling words of vanity, they allure through the lusts of the flesh, through much wantonness, those that were clean escaped from them who live in error.