After all our trials have ceased, our life will be taken up entirely with God’s praises. Therefore, it is our custom to commemorate this peaceful and blissful state by chanting Alleluia more frequently and joyfully during these fifty days.

In the book of Revelation, John the Evangelist says that he heard the throngs of heavenly powers singing this word. And the venerable father, Tobit, perceiving something of the glory of the citizens on high and the splendor of the heavenly Jerusalem, described it with these mystical words:

All the streets shall be paved with white and clean stones,and, Alleluia shall be sung in its streets. (Tobit 13:22)

St. Bede the Venerable
Quoted in: Your Hearts Will Rejoice
Ludolph of Saxony, Carthusian