'Sign' in the Bible

As for the firepans of those who sinned at the cost of their own lives, make them into hammered sheets as plating for the altar, for they presented them before the Lord, and the firepans are holy. They will be a sign to the Israelites.”

The Lord told Moses, “Put Aaron’s staff back in front of the testimony to be kept as a sign for the rebels, so that you may put an end to their complaints before Me, or else they will die.”

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