Mark 9:48

"Where their worm dieth not, and the fire is not quenched."

Cross References (ranked by relevance)

And they shall go forth, and look upon the carcases of the men that have transgressed against me: for their worm shall not die, neither shall their fire be quenched; and they shall be an abhorring unto all flesh.

Matthew 25:41

Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels: