As a matter of fact the Benedictus es Domine was sung daily in the ambrosian Rite at Matins, and is found also in the Mozarabic Breviary.
"A Short History of the Book of Common Prayer"
William Reed Huntington
The very ambrosian music which is now so strange to modern ears was doubtless, when St. Ambrose introduced it, much akin to the secular music of the day, if it was not directly borrowed from it: and the history of hymn-music is a history of the adaptations of profane successes in the art to the uses of the Church.
"A Practical Discourse on Some Principles of Hymn-Singing"
Robert Bridges
An ambrosian Advent Hymn Come, Thou Saviour of our race, Choicest Gift of heavenly grace!
"The Story of Our Hymns"
Ernest Edwin Ryden