28 A worthless witness mocks at justice,
and the mouth of the wicked devours iniquity.
29 Condemnation is ready for scoffers,
and beating for the backs of fools.
In verse 28, we learn what scoffers are like, and in verse 29 we see the judgment, which the Lord will bring upon them.
The scoffer or mocker has no concern for the truth. Language is something the scoffer uses to bring about the political or judicial or personal ends he wants. In his eyes, language is not about truth, but about power. He uses words/lies to get what he wants. The scoffer has no fear of God and no respect for man (Luke 18:2). His lack of reverence for the Lord, leads to his lack of respect for God's image bearers. Thus, even under oath he will lie because he does not revere God's name.
But verse 29 teaches that the Lord will judge scoffers. Those who mock justice, will one day receive justice from the Lord. And if they refuse to repent in this life of their wickedness, then the justice they receive will be eternal and infinite, since they have sinned against an eternal and infinite God. Repentance means a man judges and condemns himself, so that he won't incur God's condemnation and judgment. Hell is the conscious, everlasting torment that sinners deserve for their sins against their Maker for living a life that did not reverence God, nor love their fellow men, especially those of the household of faith (Matthew 25:31-46).
One application of this proverb is to remember both the severity of the law and the sweetness of the gospel. There is a false, heretical message that comes to us under the guise of Christianity, but itt lacks the courage to tell people the truth that the same Lord who is faithful to save is also faithful to judge. A faithful messenger for the Lord preaches both the law and the gospel. Peter himself told us this in Acts 10:
Faithful, apostolic teaching and preaching must include the judgment and wrath to which the broken law of God leads. Thus, the severity of the law.
But Peter immediately moves from proclaiming judgment to proclaiming the gospel:
The law accuses us and threatens us with God's judgment, but the gospel removes his judgment for all who will judge themselves and turn to Christ in faith. Thus, the sweetness of the gospel.