Matthew Henry's Complete Bible Commentary
Verses 29—30
Here is another sort of evil men described to us, that we may neither do like them, nor have any thing to do with them. 1. Such as (like Satan) do all the mischief they can by force and violence, as roaring lions, and not only by fraud and insinuation, as subtle serpents: They are violent men, that do all by rapine and oppression, that shut their eyes, meditating with the closest intention and application of mind to devise froward things, to contrive how they may do the greatest mischief to their neighbour, to do it effectually and yet securely to themselves; and then moving their lips, giving the word of command to their agents, they bring the evil to pass, and accomplish the wicked device, biting his lips (so some read it) for vexation. When the wicked plots against the just he gnasheth upon him with his teeth. 2. Such as (like Satan still) do all they can to entice and draw in others to join with them in doing mischief, leading them in a way that is not good, that is not honest, nor honourable, nor safe, but offensive to God, and which will be in the end pernicious to the sinner. Thus he aims to ruin some in this world by bringing them into trouble, and others in the other world by bringing them into sin. MHBCC 645.27