'Sign' in the Bible

O ye children of Benjamin, gather yourselves to flee out of the midst of Jerusalem, and blow the trumpet in Tekoa, and set up a sign of fire in Bethhaccerem: for evil appeareth out of the north, and great destruction.

And this shall be a sign unto you, saith the LORD, that I will punish you in this place, that ye may know that my words shall surely stand against you for evil: