And the earth opened its mouth and swallowed them along with Korah, whose followers died when the fire consumed 250 men. They serve as a warning sign.

Numbers 16:32
and the earth opened its mouth and swallowed them and their households--all Korah's men and all their possessions.

Numbers 16:35
And fire came forth from the LORD and consumed the 250 men who were offering the incense.

Numbers 16:38
As for the censers of those who sinned at the cost of their own lives, hammer them into sheets to overlay the altar, for these were presented before the LORD, and so have become holy. They will serve as a sign to the Israelites."

Deuteronomy 11:6
and what He did in the midst of all the Israelites to Dathan and Abiram, the sons of Eliab the Reubenite, when the earth opened its mouth and swallowed them, their households, their tents, and every living thing that belonged to them.

Deuteronomy 28:46
These curses will be a sign and a wonder upon you and your descendants forever.

And the earth opened her mouth, and swallowed them up together with Korah, when that company died, what time the fire devoured two hundred and fifty men: and they became a sign.