I’m going to dip in an out of all the songs for the Daily Office – many are merely antiphons for narrow purposes – but essential if you are doing these prayers all the time.
This is a whole song, though, and is a morning office hymn.
The text. by James Quinn, is here (CWB II omits the second verse).
CWB II set this song to SPLENDOUR (aka PUER NOBIS NASCITUR) by Michael Praetorius.