This is another Carol E. Browning song for Lent in Gather 3rd ed. She used The Jesus Prayer as a refrain and the Agnus Dei and Psalm 51 for the verses.
The assembly sings the ostinato refrain and a cantor can sing the verses over the top of them. I’m never sure if the songs that haven’t made it into more common use from collections like these are used less because of the need for a cantor or because they were written by a woman.
GIA will sell you the sheet music and the text is in their preview.