Mark 9:48-49

where their worm never dies and the fire is never put out.

Hebrews 10:27

nothing but an awful outlook of doom, of that burning Wrath which will consume the foes of God.

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 their worm never dies and the fire is never put out.
Hebrews 10:27
nothing but an awful outlook of doom, of that burning Wrath which will consume the foes of God.