'Sign' in the Bible

Then for your part take an iron frying pan and set it up as an iron wall between you and the city. Set your face toward it. It is to be under siege; you are to besiege it. This is a sign for the house of Israel.

When the scouts survey the land and see a human bone, they will place a sign by it, until those assigned to burial duty have buried it in the valley of Hamon-Gog.