Luke 3:16-17

16John answered them all by saying, “As for me, I baptize you [only] with water; but One who is mightier [more powerful, more noble] than I is coming, and I am not fit to untie the strap of His sandals [even as His slave]. He will baptize you [who truly repent] with the Holy Spirit and [you who remain unrepentant] with fire.

17His winnowing fork is in His hand to thoroughly clear His threshing floor, and to gather the wheat (believers) into His barn (kingdom); but He will burn up the chaff (the unrepentant) with unquenchable fire.”