Verbum Supernum Prodiens Wikipedia
Verbum Supernum Prodiens is a Catholic hymn in long metre by St Thomas Aquinas. It was written for the Hour of Lauds in the Divine Office of Corpus Christi. It is about the institution of the Eucharist by Christ at the Last Supper, and His Passion and death.
The last two verses form a hymn on their own as well, O Salutaris Hostia, which is sung at the Adoration of the Blessed Sacrament.
There is also an unrelated Latin Nativity hymn of the same name.