Grande Munus §8

⁸ Cyril and Methodius then recounted to the Supreme Pontiff and his clergy the apostolic mission they had fulfilled with so much holiness and labor. They were accused of acting in opposition to ancient customs and contrary to holy rites in making use of the Slavic language for religious matters. However, they pleaded their cause with such indisputable and noble reasoning that the pope and all the clergy praised them and approved their course of action. Both then took an oath in the Catholic manner and swore that they would remain in the faith of St. Peter and of the popes. After that they were created bishops and consecrated by Adrian himself, and many of their disciples were raised to different grades in Holy Orders. Death of Cyril