Matthew 24:

23 Then if any man shall say unto you, Lo, here is Christ, or there; believe it not.

24 For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.
signs 2nd Thess 2:9, Rev 13:13

25 Behold, I have told you before.

26 Wherefore if they shall say unto you, Behold, he is in the desert; go not forth: behold, he is in the secret chambers; believe it not.