Saint Casilda was the daughter of King Ismail al-Zafir, the Islamic king of Toldeo. Christian's at the time were frequently arrested and placed in terrible prison conditions and this weighed heavily on Saint Casilda's heart. Soon she began sneaking loaves of bread into the prison housing them, hiding the loaves in her dress so that they would not starve. As she snuck bread into the prison one night, her father's guards caught site of her and demanded she reveal what was hidden underneath her dress.
Saint Casilda slowly opened her dress, knowing the punishment that would be fall her if her father knew she was sneaking bread to the Christian prisoners. The bread in her dress miraculously turned into a bouquet of beautiful roses.
As she grew older into a young adult, she fell ill (the specifics of the illness are not known). She refused help from the Arabian doctors that were at her father's disposal and instead traveled to the waters at the shrine of San Vicente. These waters were very well known throughout Iberia for their miraculous healing. She climbed into the water slowly, and as she did she could feel the illness leaving. So moved by the miracle she asked to be baptized. In the near town, Burgos, she was baptized by a Christian priest and began to live a solitary life near the spring. Tradition holds she lived to be 100 years ago.
Saint Casilda is venerated both in the Roman Catholic and Eastern Orthodox churches.