Ave verum is a Latin prayer from the 13th century. The writer of the words is unknown. The content is about the Eucharist, based on the Catholic doctrine that the Body of Christ becomes present through consecration of bread and wine. Many composers in history wrote music according to the words - the most famous version was written by Wolfgang Amadeus Mozart. His composition "Ave verum" for choir, strings and organ gained currency beyond clerical occasions.
You can perform this piece with concert band and choir (ad lib.) with Latin lyrics.