Augustine of Hippo

"You shall sprinkle me," he says, "with hyssop, and I shall be cleansed" [Psalm 51:7]. Hyssop we know to be a herb humble but healing: to the rock it is said to adhere with roots. Thence in a mystery the similitude of cleansing the heart has been taken. Do thou also take hold, with the root of your love, on your Rock: be humble in your humble God, in order that you may be exalted in your glorified God. You shall be sprinkled with hyssop, the humility of Christ shall cleanse you. …

Exposition on Psalm 51 ↗

Ambrose of Milan

After this white robes were given to you as a sign that you were putting off the covering of sins and putting on the chaste veil of innocence, of which the prophet said, "Purge me with hyssop, and I shall be cleansed; wash me, and I shall be made whiter than snow." For one who is baptized is seen to be purified according to the law and according to the gospel: according to the law, because Moses sprinkled the blood of the lamb with a bunch of hyssop; according to the gospel, because Christ's garments were white as snow, when in the …

On the Mysteries 7:34 ↗

Thomas Aquinas

"You shall sprinkle me with hyssop." Above, the Psalmist commemorated the benefit of God granted to him as to the grace of prophecy, from which he was raised to hope; here he shows what he hoped for from God. And there were two things. First, he hopes for the removal of the evils he had incurred through sin. Second, he hopes for the restoration of the goods he had lost, at "to my hearing." It should be known that through sin a person first incurs uncleanness. Jer. …

Exposition on the Psalms of David ↗