Galatians 1:8-10

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). As we have previously said, and now again I say, if any one preaches a “Besuras HaGeulah” to you other than that which you received, let him be ARUR HAISH and be consigned to onesh Gehinnom. Am I now seeking the ishshur (approval) of Bnei Adam? Or the haskama (approval) of HASHEM? Or am I seeking to be a man-pleaser? If [and this is not the case] I were still pleasing Bnei Adam, I would not have been the eved of Moshiach.