One of the knights at the Round Table, the only one who had a truly faithful wife. This was made clear with the help of a magic cape which suited perfectly on faithful wifes - Queen Guinevere tried it once, and then it was either to short or to long - as well as a drinking-horn from which no decieved husband could drink without spilling.
Casadoc and his wife were the only ones at Arthur's court who could handle these things.
Chastity Test | The Legend of King Arthur
Morgan's Drinking Horn | The Legend of King Arthur