19 Since then the Body of Christ is in the end to be severed in body also from the unholy and wicked, but now meanwhile groans among them, what does the “love of Christ among the daughters, as the lily among thorns”? What are her words? What her conscience? What is the “appearance of the king's daughter within”? Lo, hear what she says. “Prove me, O God, and know my heart”. Do Thou, O God, Thou prove me, Thou know; not man, not an heretic, who neither knows how to prove, nor can know my heart, whereas You prove, and know that I consent not to the deeds of the wicked, while they think that I can be defiled by the sins of others; so that, while I in my long wandering do what I mourn in another Psalm, that is, while I “labour for peace among them that hate peace,” until I come to that Vision of peace, which is called Jerusalem, “which is the mother of us all,” the city “eternal in the heavens;” they, contending, and falsely accusing and separating themselves, may “receive,” not, evidently, in eternity, but “in vanity, their cities.” Why this? Observe what follows.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)