This is the tenor aria from Vivaldi’s RV 588, sometimes referred to as the “Little Gloria”.  It also happens to be a piece that I’m learning. :)

The Domine Deus tenor aria from Antonio Vivaldi’s Gloria, RV 588, composed likely in the 1710s–1720s for Venice’s Ospedale della Pietà, is a concise yet poignant sacred piece that marries devotional intensity with Baroque expressiveness. Sung by a tenor, accompanied by strings and continuo, it sets the text “Domine Deus, Rex coelestis, Deus Pater omnipotens” with a lyrical melody that balances solemn reverence and subtle virtuosity, its restrained ornamentation amplifying the text’s spiritual weight. The strings’ rhythmic vitality and dynamic interplay create a conversational texture, while the continuo provides harmonic depth, crafting an intimate, prayerful dialogue that lasts under four minutes. Though less celebrated than its RV 589 counterpart, this aria’s clarity and emotional directness exemplify Vivaldi’s genius in humanizing sacred music for liturgical performance.