Augustine of Hippo

"The generation to come shall be declared to the Lord" [Psalm 22:31]. The generation of the New Testament shall be declared to the honour of the Lord. "And the heavens shall declare His righteousness." And the Evangelists shall declare His righteousness. "To a people that shall be born, whom the Lord has made." To a people that shall be born to the Lord through faith.

Exposition on Psalm 22 ↗

Bede

The saints who are aflame with desire for heavenly things are fittingly called "the heavens," as the psalmist says, "And the heavens will proclaim his justice to a people yet to be born," which is to say, "And the most illustrious teachers will proclaim, with mind, voice and action, his justice to a people, who, coming recently to the faith, desire to be born in him."

Homilies on the Gospels 2:17 ↗

Thomas Aquinas

"It shall be proclaimed." Here he explains when this will happen: not in his own time, but in future times. And he sets forth three things. First, he foretells the preaching of the faith. Second, by whom it must be preached. Third, to whom it is preached. Regarding the first he says, "A generation to come shall be proclaimed to the Lord"; and this can be expounded in two ways. In one way, with Jerome: as if to say, a coming generation shall be proclaimed, that is, evangelized. …

Exposition on the Psalms of David ↗