Arthur appears in the Vitae or "biography" of St. Cadoc himself. A pressured Arthur aids the saint's mother in eloping with her lover, though Arthur lusts after her himself. Cadoc is the result of this elopement.
Many years later, as abbot of Llancarfan, Cadoc grants seven years of sanctuary to a man who has slain three of Arthur's men. Arthur disputes this but is eventually silenced by a miracle and he accepts Cadoc's authority.
This second tale brings up certain chronological issues. In it, Arthur is called King of Britain, hinting at a political system that could not have existed into the 6th century. However, by making him a contemporary with not only the Abbot Cadoc but St. David as well, it puts Arthur well into the 6th century and much, much later than the reputed date of the battle of Camlann.
Cadoc's "life" is a perfect example of the extension of Arthur's career prevalent in Welsh legend and the historical problems created by such aggrandizing.