Augustine of Hippo

"But I, in the multitude of Your mercy, will enter into Your house." "In the multitude of mercy:" perhaps he means in the multitude of perfected and blessed men, of whom that city shall consist, of which the Church is now in travail, and is bearing few by few. Now that many men regenerated and perfected, are rightly called the multitude of God's mercy, who can deny; when it is most truly said, "What is man that You are mindful of him, or the son of man that You visit him? …

Exposition on Psalm 5 ↗

Jerome

But I, in the multitude of Thy mercy, will enter into Thy house. They in their iniquity go out from Thy house: I in Thy mercy enter into Thy house. I will enter into Thy house, which is the Church. I will worship toward Thy holy temple in Thy fear. That is the house which is also the temple.

Homily 2, on Psalm 5 ↗

Thomas Aquinas

Next, when he says "But I," he shows how he stands before the Lord; and concerning this he does two things. First, he shows how he approaches God. Second, what prayer he offers, at "I will worship." Someone might therefore say to him: You say that the malicious one will not dwell beside you. But are you not a sinner? How then will you stand? …

Exposition on the Psalms of David ↗