The brief little SATB piece, O Pater Sancte (PDF), has been requested by many. The full title is O Pater Sancte, Mitis Atque Pie (“Father most holy, gracious and forgiving”). The melody occurs many times in the The Saint Jean de Brébeuf Hymnal—including on page 724 with a fabulous translation by Monsignor Knox. The tune is called “Iste Confessor,” and you can learn more here.
Harmonies are © Brébeuf Hymnal (2018)