Thomas Aquinas, on Ps 54:9

“I waited for him that hath saved me from pusillanimity of spirit, and a storm.”

“"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).”

Imported from an open dataset — not yet checked against the printed edition.