Maen Cetti, on Cevn-y-bryn, in Gower, was, says ancient tradition, adored by the pagans; but Saint David split it with a sword, in proof that it was not sacred; and he commanded a well to spring from under it, which flowed accordingly. After this event, those who previously were infidels, became converted to the Christian faith. There is a church in the vicinity, called Llanddewi, where it is said that St. David was the rector, before he became consecrated a bishop; and it is the oldest church in Gower.
From ‘Iolo Manuscripts: A Selection of Ancient Welsh Manuscripts, in Prose and Verse’ by Taliesin Williams and completed by Rev. Thomas Price (1848).