Psalms 5:9

For there is no faithfulness in their mouth - There is nothing in them which can be confided in; nothing in their promises and declarations. They are false and treacherous, and I can, therefore, only appeal to thee. It is easy to see the propriety of this statement, and of those which follow, on the supposition that this refers to the rebellion of Absalom. Absalom had gone to Hebron on a false pretence 2 Samuel 15:7, and every act of his in this whole transaction had been treacherous and false.

Their inward part - Not only their external conduct, but their hearts, their principles, their motives. This was fairly to be inferred from their conduct. The object of the psalmist is to show that they were wholly depraved in all that properly constitutes character or that entered into moral conduct.

Their throat is an open sepulchre - That is, as the grave is open to receive its victim, so is their throat open to devour or swallow up the peace and happiness of others. The main idea is that they are false, treacherous, not to be confided in, slanderous. This passage, with the following, is employed by the apostle Paul to demonstrate the universal depravity of man. See the notes at Romans 3:13.

They flatter with their tongue - He had referred to the “inward part,” or the “heart,” and to the “throat” as being depraved and evil; he now refers to another member of the body as being equally depraved - the “tongue.” Instead of being employed to utter truth, and to give expression to the real feelings of the heart, it was employed to flatter others, with a view to lead them astray, or to make use of them for base and selfish purposes. The propriety of this representation as applicable to Absalom and his coadjutors no one can fail to see (compare 2 Samuel 15:1). It is also to an eminent degree the characteristic of the wicked in general. On this, also, see the notes at Romans 3:13.