See, the problem is that the liars really do have gut wrenching fear- as all liars do- and they confuse that fear as being caused by some 'unknown' outside danger - rather than the fear that all liars have- of knowing that they have done evil and deserve to be condemned.
It is that condemnation, coming from within their own souls, that is the basis of their fear. How does one live with oneself, when oneself is the very source of the most damning judgement ?
That is their real problem - and they are blind to it -as with Pharaoh, first they have hardened their own hearts, and then G_d steps in to seal the deal ...forever.
Call their fear a small unknowing glimpse into things to come.

Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good ...