'Sign' in the Bible

As for the censers of these people who have sinned at the cost of their lives, have the censers made into hammered sheets as a plating for the altar [of burnt offering], for they were presented before the Lord and they are sacred. They shall be a [warning] sign to the sons of Israel.”

But the Lord said to Moses, “Put Aaron’s rod back before the Testimony [in the ark], to be kept as a [warning] sign for the rebellious and contentious, so that you may put an end to their murmurings [of discontent] against Me, so that they do not die.”

and the earth opened its mouth and swallowed them up along with Korah, when that company died, when the fire devoured two hundred and fifty men, so that they became a [warning] sign.