Hymn for Vespers from the Ascension to Pentecost. From the Ambrosian school, 7th or 8th century. There are about 30 translations; the English title given is by T. Potter. The second stanza reads:

What nameless mercy Thee o'ercame.

To bear our load of sin and shame

For guiltless, Thou Thy life didst give,

That sinful erring man might live.