This is the psalm for The Assumption of the Blessed Virgin Mary. Unlike most of Mason’s psalms, I don’t think it has general use a hymn elsewhere, it’s text is too specific to its situation.
The sheet music is available in Paul Mason’s collection Psalms for All Time. If you don’t have the text in your missal, it’s the same as in Kate Keefe’s setting.
I’m sure this backing is much use except for listening to the tune.