Augustine of Hippo

"For the Lord shall give sweetness, and our land shall give her increase" [Psalm 85:12]....He will give unto you the sweetness of working righteousness, so that righteousness shall begin to delight you, whom before unrighteousness delighted: so that thou who at first delighted in drunkenness, shall rejoice in sobriety: and thou who at first rejoiced in theft, so as to take from another man what you had not, shall seek to give to him that has not that which you have: and thou who took delight in robbing, shall delight now in giving: …

Exposition on Psalm 85 ↗

Jerome

And so, that you may know that "righteousness" does not sound of cruelty, but of mercy, see what it says. For the Lord shall give loving-kindness. For this reason He looked down from heaven, that He might have mercy on His works. And our land shall yield its fruit. Truth indeed has sprung up out of the earth: this of the past. Now it is said of the future, And our land shall yield its fruit. Do not despair, because He was once born of Mary: daily He is born also in us. And our land shall yield its fruit. …

Homily 17, on Psalm 84 ↗

Bonaventure

And so, concerning the fruit of grace, it is written in the Psalm: "For the Lord will give goodness: and our earth shall yield her fruit." And so these fruits come forth from Christ, blessed by Joseph who produced fruit of heaven, and of the dew, and of the deep that lieth beneath, that is, the charismatic gifts of the graces, by means of dew on humble hearts.

Collations on the Hexaemeron, Collation 18 ↗