Numbers 16:38
The censers of these sinners against their own souls, let them make them broad plates for a covering of the altar: for they offered them before the LORD, therefore they are hallowed: and they shall be a sign unto the children of Israel.
Numbers 26:10
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.