Thomas Aquinas, on Ps 39:10

“I have declared thy justice in a great church, lo, I will not restrain my lips: O Lord, thou knowest it.”

“With regard to Christ, when he says, "I have not hidden your justice in my heart." He confesses the teachings of truth when he says, "Your truth." This Christ confessed before Pilate. Jn. 18: "For this I was born and for this I came into the world, that I might bear witness to the truth": Prov. 8: "My throat shall meditate on truth." "And I have declared your salvation," because through the confession of truth salvation comes to a person: Joel 2: "Everyone who calls upon the name of the Lord shall be saved." He confesses the benefits of mercy when he says, "I have not hidden your mercy and your truth": because mercy and truth follow one another; and therefore he says "truth." It is not placed here for the truth of doctrine, but for the truth of justice in promises: because God is truthful. Truth, however, consists in this: that he gives what he promises, because he is not otherwise our debtor except insofar as he promises.”

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