Augustine of Hippo

"You will protect them in Your tabernacle from the contradiction of tongues" [Psalm 31:20]. But here meanwhile while evil tongues murmur against them, saying, Who has come thence? You will protect them in the tabernacle, that of faith in those things, which the Lord wrought and endured for us in time.

Exposition on Psalm 31 ↗

Thomas Aquinas

Then when he says, "You will hide them," he shows the benefits of God toward the saints through liberation from evil. But because man can suffer a twofold evil -- namely, in deed and in word -- first he shows when he protects from the first evil. Second, how from the second, at "You will protect them." He says therefore, "You will hide them," and so on. He speaks by way of similitude: just as if someone were sought for death, whoever hid him in the secret places of his house, there he would be safe. So it is with the saints. …

Exposition on the Psalms of David ↗

Bonaventure

He who fears God cannot lose God. But he who fears something other than God has what ought to be taken from him. But he who fears God is secure everywhere. "How great is the multitude of your sweetness, O Lord, which you have hidden for those who fear you; you have perfected it for those who hope in you." Therefore the fear of God ought to be perfect, because "it shall be well with those who fear God," because they shall come to the blessing of glory.

Collationes de Septem Donis, Collation 2 ↗