Mark 9:48-49

where the worm that feeds upon them never dies and the fire is never put out.

Hebrews 10:27

but only a terrifying prospect of judgment and that fiery indignation which is going to devour God's enemies.

Treasury of Scripture Knowledge

Summary

And the fire upon the altar shall be burning in it; it shall not be put out: and the priest shall burn wood on it every morning, and lay the burnt offering in order upon it; and he shall burn thereon the fat of the peace offerings.

Bible References

The fire

Mark 9:48
where the worm that feeds upon them never dies and the fire is never put out.
Hebrews 10:27
but only a terrifying prospect of judgment and that fiery indignation which is going to devour God's enemies.