Thomas Aquinas, on Ps 39:9

“That I should do thy will: O my God, I have desired it, and thy law in the midst of my heart.”

“"I have proclaimed your justice in the Church." Here the manner of proclaiming is presented. Three things, therefore, we ought to proclaim about divine matters: namely the works of justice, the teachings of truth, and the benefits of divine mercy; and these three things he says he has proclaimed. First, he says he has proclaimed the works of justice: "I have proclaimed your justice," which he proclaimed or preached in three ways: publicly, readily, and purely. As to the first he says, "In the great Church." Likewise, in a gathering of many: Jn. 18: "I have spoken openly to the world." Or, "in the great Church," that is, in the Catholic Church, because it is great in power and stability: Mt. 16: "The gates of hell shall not prevail against it." And great in extent: Mal. 1: "From the rising of the sun to its setting, great is your name." As to the second he says, "Behold, I will not restrain my lips"; as if to say, I will not yield to those who forbid: Acts 4: "Grant to your servants to speak your word with confidence." As to the third he says, "You know," that is, you have approved my intention: Jer. 18: "You know all their counsel." Or, "You know," that is, you predestined from eternity.”

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