John Calvin Commentary Psalms 5:9

"For there is no faithfulness in their mouth; Their inward part is very wickedness; Their throat is an open sepulchre; They flatter with their tongue." — Psalms 5:9 (ASV)

For there is no faithfulness in their mouth. He still repeats the same complaints he made before, intending by this to render his enemies more odious in the sight of God, and to call forth on his own behalf the mercy of God, who has promised to help those who are unjustly oppressed.

And we should pay particular attention to this: the more our enemies show their cruelty against us, or the more wickedly they trouble us, the more confidently we should send up our groans to heaven. God will not allow their rage to go to the extreme, but will bring their malice and wicked schemes to light.

In the first place, he accuses them of treachery, because they speak nothing that is upright or sincere; and the reason he gives for this is that inwardly they are full of iniquity. He next compares them to tombs, their throat is an open sepulcher; as if he had said, they are devouring gulfs, meaning by this their insatiable desire to shed blood.

At the end of the verse, he again speaks of their deceitfulness. From all this we conclude that the wrongs he endured were not ordinary, but that he had to contend with most wicked enemies who had neither humanity nor moderation. Being so miserably oppressed, he not only perseveres in prayer but also finds reason for hope even in the confusion and apparent hopelessness of his outward condition.

When Paul (Romans 3:13), in quoting this passage, extends it to all mankind, both Jews and Gentiles, he does not give it a broader meaning than the Holy Spirit intended. He considers it an undeniable point that in the person of David, the church is described to us here—both in the person of Christ, who is the head, and in his members. It therefore follows that all those who have not been regenerated by the Spirit of God should be counted among his enemies, whether they are outside the boundaries of the visible church or within it.

For David, in this passage, does not summon either the Assyrians or the Egyptians to the judgment seat of God, but the degenerate Jews, who, being circumcised in the flesh, gloried in their descent from the holy lineage of Abraham. Paul, therefore, does not twist these words from their genuine meaning when he applies them to all mankind, but truthfully asserts that David showed in them what is the character of the whole human family by nature.