Galatians 1:8

But even if we or a malach from Shomayim should pose as maggidim [for Moshiach] and make a hachrazah (proclamation) to you of a “Besuras HaGeulah” other than that Besuras HaGeulah which we preached to you, let such a one be ARUR HAISH (Cursed is the man) and set under cherem (ban of destruction) and onesh Gehinnom (damnation).