Thomas Aquinas, on Ps 54:1

“Unto the end, in verses, understanding for David.”

“"Hear, O God, my prayer, and do not despise." Above, the Psalmist showed the assault of enemies against himself. Here he sets forth deliverance from them. And first he asks in general against all enemies. Second, he asks specifically against certain ones, at "Rescue me from my enemies." Concerning the first, he does two things. First, he implores God's help against the evils he suffers from enemies. Second, having been heard, he gives thanks, at "Have mercy on me, O God, have mercy on me." Concerning the first, he does two things. First, he amplifies the evils he suffers with respect to sorrow. Second, with respect to the persistence of tribulation: "Have mercy on me, O God, for he has trampled on me." In this Psalm, according to the Gloss, the Psalmist speaks in his own person, expressing the very tribulations he was suffering. It can also be said in the person of the Church, or of a just man, or of Christ insofar as he bears the figure of our weakness. The title: "Unto the end, in verses, an understanding of David." And the sense is: "an understanding of David," as if to say: this is the understanding of David, in verses. And it is titled from "understanding," so that he who is in tribulation may know how to recognize the evils he suffers and the good things he expects, according to Prov. 14: "The heart that knows its own bitterness," etc. This Psalm is therefore divided into three parts. First, he explains the tribulation he was suffering. Second, the malice of the enemies, at "Cast them down." Third, he commemorates the help God provided him, at "But I cried to God." Concerning the first, he does two things. First, he asks that his prayer be heard. Second, he explains the tribulation, at "I was saddened." He says, therefore, "Hear, O God, my prayer." This is when the one who prays asserts what he is asking by repeating his prayer. Nor is this superfluous, because the repetition of prayer stirs up the affections. Jas., last chapter: "It avails much," etc. Sometimes, moreover, what is asked is obtained even when the prayer is not acceptable to God, as when a sinner asks; but in the very fact of asking, he merits God's displeasure. Ps. (77): "He gave them their requests and sent satiety into their souls," etc. "But while the food was still in their mouths, the anger of God ascended upon them." Frequently someone grants in anger what he denies when favorable. And therefore he says, "and do not despise my supplication." Someone's prayer is despised for two reasons: either because he asks what ought not justly to be asked, or because he asks not devoutly but with pride. Ps. (101): "He has regarded the prayer of the humble and has not despised it," etc. The prayer of the Pharisee was despised because he asked with pride (Lk. 18). Ps. (140): "Let my prayer be directed," etc.”

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