This is a hymn "Hallelujah" from the Orthodox Matins Service of Holy Week (The Monday, Tuesday, and Wednesday before Easter Sunday - Pascha). It's traditionally done on the evening of Sunday, Monday, and Tuesday in anticipation of the next morning. The text is: "Alleluia. Alleluia. Alleluia. Behold, the Bridegroom cometh at midnight and blessed is the servant whom He shall find watching, but unworthy is the servant whom He shall find heedless. Beware, therefore, O my soul, do not be laid down with sleep, lest you be given up to death, and be shut out of the Kingdom. But rouse yourself, crying: Holy, Holy, Holy, art Thou, O God! Through the Mother of God, have mercy on us!"

Here is a link to "The Colors of Grace" performed by the St. Francis Choir on March 24, 2024.

https://fb.watch/r0M81m7dl-/

Deo Gratias. We praise Thee. To Thee we sing and give thanks.
Let us now lay aside all earthly care.