The New Testament mentions singing hymns during the Last Supper: When they had sung the hymn, they went out to the Mount of Olives (). Other ancient witnesses such as Pope Clement I, Tertullian, St. Athanasius, and Egeria confirm the practice, although in poetic or obscure ways that shed little light on how music sounded during this period. The 3rd-century Greek Oxyrhynchus hymn survived with musical notation, but the connection between this hymn and the plainchant tradition is uncertain.