Once grown, Cadoc was deeply religious and, according to some sources, it was his example and preaching that persuaded Gwynllyw to abandon his life of violence and to seek forgiveness for his sins. King Gwynllyw then had a dream in which an angel spoke to him and he saw a vision of a white ox with a black spot on its high forehead. Gwynllyw went forth and when he saw the same ox as in his dream he founded a hermitage there on what is now Stow Hill in Newport, South Wales which he built out of wood. Gwynllyw said of the spot: "There is no retreat in the world such as in this space which I am destined now to inhabit. Happy therefore is the place, happier then is he who inhabits it." Gwynllyw's decision to abandon his kingship and retire to a religious life seems to have been a common theme amongst Welsh saints and even his violent past was not unusual, being shared by Saint Illtyd amongst others.