Psalms 64:3

“Who whet their tongue like a sword, etc.] Use cutting, wounding, killing, and devouring words; on which they set an edge, and make them keener and keener to hurt and ruin the characters and reputations of good men, and grieve and distress their minds; [and] bend [their bows to shoot] their arrows, [even] bitter words; such are the these doctrines of heretical men, which are roots of bitterness, that defile some and trouble others; such are the oaths and curses of profane sinners, whose mouths are full of cursing and bitterness; and such are the blasphemies of antichrist against God, against his tabernacle, and against them that dwell therein; and such are the hard speeches spoken by ungodly…”

“Similar figures for slander (Psa 57:4; Psa 59:7). bend--literally, "tread," or, "prepared." The allusion is to the mode of bending a bow by treading on it; here, and in Psa 58:7, transferred to arrows.”

“Who whet their tongue like a sword - Who sharpen their tongue; that is, they utter words that will cut deep, or penetrate the soul. The idea is that of slander or reproach - the same idea which we have in Shakespeare (Cymbeline): “‘Tis slander; Whose edge is sharper than the sword.” This comparison is a favorite one with David. Compare Psalms 52:2; Psalms 57:4; Psalms 59:7. And bend their bows ... - That is, they prepare for this - as they make ready to shoot who bend their bows, and fix their arrows on the string. The idea here is, that this was deliberate, or was the result of counsel and purpose. It was not an outbreak of mere passion and excitement; it was by fixed design and careful…”

“64:3 their tongues . . . bitter words: Liars use their speech to kill. This description might also refer to practicing magic.”

“whet: Psa 57:4; Pro 12:18, Pro 30:14; Isa 54:17; Jer 9:3; Jam 3:6-8 bend: Psa 11:2, Psa 58:7 Psalms 64:4”