They have set their mouth against heaven: and their tongue hath passed through the earth.

“Hence we should know that the Holy Spirit has condemned those detestable people who hold such views. For what other people does he specifically condemn except the Arians, who say that the Son of God does not experience periods of time and years? For there isn't anything with which that God is not familiar. If, however, Christ is God and Christ is the highest God, then he is God above all things. Notice how outraged the blessed David was with such people who limit the Son of God's knowledge. He says, "They do not share the troubles common to human beings, and they will not be plagued like other people. They are burdened with their pride; they are clothed in iniquity and impiety. Their iniquity is proportionate with their portliness. They extend into the condition of the heart." Without a doubt he condemns those who believe that divine things must be determined from the "condition of the heart." For God is not subject to [any temporal] condition or order because these are things that are peculiar to human beings and according to succeeding generations. But we know that they do not always occur according to some formal plan but more often happen according to some secret and hidden mystery."They have thought," he says, "and they have spoken wickedly and sinfully against God. They have set their mouth against heaven." And so we see that he condemns those who are responsible for impious blasphemy and who claim for themselves the right to arrange the secrets of heaven according to the manner of human nature.”

“"They have set against Heaven their mouth, and their tongue hath passed over above the earth" (ver. 9). For this, "hath passed over above the earth" is, they pass over all earthly things? What is it to pass over all earthly things? He doth not think of himself as a man that can die suddenly, when he is speaking; he doth menace as if he were alway to live: his thought doth transcend earthly frailty, he knoweth not with what sort of vessel he is enwrapped; he knoweth not what hath been written in another place concerning such men: "His spirit shall go forth, and he shall return unto his earth, in that day shall perish all his thoughts." But these men not thinking of their last day, speak pride, and unto Heaven they set their mouth, they transcend the earth. If a robber were not to think of his last day, that is, the last day of his trial, when sent to prison, nothing would be more monstrous than he: and yet he might escape. Whither dost thou flee to escape death? Certain will that day be. What is the long time which thou hast to live? How much is the long time which hath an end, even if it were a long time? To this there is added that it is nought: and the very thing which is called long time is not a long time, and is uncertain. Why doth he not think of this? Because he hath set against Heaven his mouth, and his tongue hath passed over above the earth. "And full days shall be found in them."”

“They set The emphasis, in place of the implication that they spoke about me and my late father with contempt, is explained as the doubling of the root "שתת" (to set or place), meaning their mouths were set in motion as if speaking in the heavens, indicating that they speak about God without knowledge of Him. And their tongue walks in the land. In other words, their actions and words, which are carried out on Earth, are observed by Heaven.”

“They set their mouth against the heavens,.... Against God in heaven, see Dan 4:26, against his being, saying, there is no God; against his perfections, thinking him to be such an one as themselves; against his purposes and decrees, replying against him, and charging him with insincerity, cruelty, and unrighteousness; and against his providence, either denying it, or affirming it to be unequal; and against his doctrines, ordinances, and ministers. Aben Ezra interprets it also of the angels of heaven, who are spoken against, when it is denied that there are any such beings, as were by the Sadducees; and blasphemed, when the worshipping of them is introduced. The Targum understands it of the saints of heaven, with which compare Rev 13:6 it may be applied to civil magistrates, the higher powers, who represent on earth God in heaven; and there are some that despise dominion, and speak evil of such dignities: and their tongue walketh through the earth: sparing none, high nor low, but injures all sorts of persons with their lies and calumnies. This denotes the unbridled liberty which wicked men take with their tongues; there is no restraint upon them, no stopping of them; see Psa 12:5 the universal mischief they are continually doing, and the diabolical influence of their detraction and falsehood; like Satan, their tongues walk to and fro in the earth, doing all the injury to the credit and characters of men they possibly can.”