According to Alcuin's Life of St. Willebrord, the saint visited an island between Frisia and Denmark that was sacred to Fosite and was called Fositesland after the god worshipped there. There was a sacred spring from which water had to be drawn in silence, it was so holy. Willebrord defiled the spring by baptizing people in it and killing a cow there. Altfrid tells the same story of St. Liudger. Adam of Bremen retells the story and adds that the island was "Heiligland", i.e., Heligoland.