Charles Ellicott Commentary Psalms 31:18

"Let the lying lips be dumb, Which speak against the righteous insolently, With pride and contempt." — Psalms 31:18 (ASV)

Silence. —As a different word is used from that translated as silent in Psalms 31:17, translate let the lying lips be made dumb.

Grievous. —Better, arrogant, as in 1 Samuel 2:3. (Compare Psalms 94:4.) So in Psalms 75:5, a stiff neck is a neck thrown impudently back.

Proudly and contemptuously. —Literally, in pride and contempt.