15. The Times for Reciting Alleluia
From the holy feast of Easter until Pentecost, let alleluia be recited without interruption both in the psalms and the responsories. 2 But from Pentecost until the beginning of Lent, it should be recited each night only with the last
six psalms.
3 However, on every Sunday outside of Lent, let the canticles, Matins, Prime, Terce, Sext, and None be recited with alleluia, but Vespers is recited instead with an antiphon.
4 The responsories, however, are never recited with alleluia except from Easter to Pentecost.