Ps 54:9

“"Sink, O Lord, and divide the tongues of them" [Psalm 55:9]. He is referring to men troubling him and shadowing him, and he has wished this thing not of anger, brethren. They that have wickedly lifted up themselves, for them it is expedient that they be sunk. They that have wickedly conspired, it is expedient for them that their tongues should be divided: to good let them consent, and let their tongues agree together. But if to one purpose there were a whispering against me, he says, all mine enemies, let them lose their "one purpose" in evil, divided be the tongues of them, let them not with themselves agree together. "Sink, O Lord, and divide the tongues of them." Wherefore "sink"? Because themselves they have lifted up. Wherefore "divide"? Because for an evil thing they have united. Recollect that tower of proud men made after the deluge: what said the proud men? Lest we perish in a deluge, let us make a lofty tower. [Genesis 11:4] In pride they were thinking themselves to be fortified, they built up a lofty tower, and the Lord divided the tongues of them. Then they began not to understand one another; hence arose the beginning of many tongues. For before, one tongue there was: but one tongue for men agreeing was good, one tongue for humble men was good: but when that gathering together did into a union of pride fall headlong, God spared them; even though He divided the tongues, lest by understanding one another they should make a destructive unity. Through proud men, divided were the tongues; through humble Apostles, united were the tongues. Spirit of pride dispersed tongues, Spirit Holy united tongues. For when the Holy Spirit came upon the disciples, with the tongues of all men they spoke, [Acts 2:4] by all men they were understood: tongues dispersed, into one were united. Therefore if still they rage and are Gentiles, it is expedient for them divided to have their tongues. They would have one tongue; let them come to the Church; because even among the diversity of tongues of flesh, one is the tongue in faith of heart.”

“"Cast them down, O Lord." In the preceding part, the Psalmist set forth the affliction he suffered from the wicked; here he treats of their malice. And first, describing the malice of sinners, he asks that it be impeded. Second, he asks that it be punished with punishment, at "Let death come." Concerning the first, he does two things. First, he asks that their malice be impeded. Second, he describes it, at "Because I have seen iniquity." The wicked have the ability and the power to do harm in two ways: namely, through the loftiness of their position, and through the agreement of many in one. And this is dangerous; and therefore a twofold remedy should be applied against it. In one way, that they be cast down from their position. In another way, that division be placed among them. Regarding the first, he asks, "Cast them down, O Lord," namely by removing them from their position; as if to say: throw them down by humbling them. Regarding the second, he says, "and divide their tongues," because their malice is first in the tongue, by which they speak grandly. 1 Sam. 2: "Do not multiply speaking lofty things." And because by speaking they consent to evil with their tongue. And the figure of such a division was in the Old Testament, where the tongues of the nations were divided (Gen. 11).”

“"Because I have seen iniquity." Here he describes their malice. And first he describes the common malice of the world. Second, the malice of a certain principal person among them. He describes the common malice of the multitude first in general. Second, in particular, at "Day and night." In a multitude there is a twofold disorder. One on the part of the rulers. The other on the part of the people. For a city is well ordered when the rulers govern justly and the people obey; otherwise it is not well disposed. And such a city is the world, in which neither do the rulers govern justly nor does the people obey. But the city of God is well ordered. In the city of the world, therefore, "I have seen iniquity and strife." I saw iniquity on the part of the rulers and judges. Is. 1: "Your assemblies are wicked." Likewise, I saw strife against the prelates. Is. 41: "Your people are like mud that is trampled upon."”