Jeremiah 9:3 - Matthew Poole's English Annotations on the Holy Bible

Bend, Heb. tread, because bows are usually kneeled or trod upon when they are bent, Jer 1 14 51:3. Like their bow; their tongues are here compared to a bow, and lies to arrows, because as a bow shoots out arrows, so doth the tongue words, Psalms 64:3. For lies, i.e. all reproachful, false, and noxious words, to the damage of one another; and so bending may be preparing, framing, and contriving that mischief which they purpose to vent with their tongues, Psalms 52:2-4 64:3, as bending is preparing the bow to do execution with the arrow. They are not valiant for the truth; equity, justice; they are as eager in the ways of falsehood as men engaged in war, but show no valour in maintaining the truth. Upon the earth, i.e. no truth in the earth in them, as we use to express ourselves; or rather more genuinely in the land wherein they live, they have no courage in what is good. They proceed from evil to evil; either in kind or in degree; they go on from bad to worse, 2 Timothy 3:13, which speaks little hopes of their repentance; the ground of all which is said here to be, their not knowing of God, as in the next clause, Judges 2:10,11 1 Samuel 2:12. The heart cannot work strongly after God where there be but mean apprehensions of him.