Which document preserves the earliest surviving text of Saint Patrick's Confessio?

The Book of Armagh preserves the earliest surviving text of Saint Patrick's Confessio.

The Book of Armagh is an illuminated Irish manuscript produced around 807. It contains religious texts in Latin and Old Irish, including copies of Patrick's Confessio and his Letter to the soldiers of Coroticus. Its Patrick material makes the manuscript especially important for studying the historical figure behind later Saint Patrick's Day traditions.

The manuscript was associated with Armagh, a major ecclesiastical center traditionally connected with Patrick. It also contains biblical material, writings about saints, and other church texts.

The Book of Armagh is sometimes confused with the Book of Kells, another famous Irish illuminated manuscript. The Book of Kells is celebrated mainly for its richly decorated Gospel text, while the Book of Armagh is particularly valuable for preserving early Patrick-related writings.