Not to become easily unsettled or alarmed by the teaching allegedly from us – whether by a prophecy or by word of mouth or by letter – asserting that the day of the Lord has already come. (NIV)
Not to allow your minds to be quickly unsettled or disturbed or kept excited or alarmed, whether it be by some [pretended] revelation of [the] Spirit or by word or by letter [alleged to be] from us, to the effect that the day of the Lord has [already] arrived and is here. (AMP)
That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand. (KJV)