Jeremiah 9:8

Their tongue is as an arrow: before, Jeremiah 9:3, it was compared to a bow, i.e. ready prepared, and furnished with materials contriving their wickedness, Psalms 11:2; and here to an arrow shot out, actually executing what they have designed. Some translate it a murdering arrow. It speaketh deceit; never speaking what they mean, that thereby they may the easier deceive the credulous; a double tongue, speaking fair when they mean to destroy, Psalms 55:21, as the next words explain it, intending to do the greatest mischief when they speak fairest. In heart he layeth his wait, Heb. in midst of him, i.e. in his very inwards, with his whole heart he contrives mischief.