[Rod-reé-go] or Roderick, King of Spain, conquered by the Arabs. He saved his life by flight, and wandered to Guadalet'e, where he saw a shepherd, and asked food. In return he gave the shepherd his royal chain and ring. He passed the night in the cell of a hermit, who told him that by way of penance he must pass certain days in a tomb full of snakes, toads, and lizards. After three days the hermit went to see him, and he was unhurt, “because the Lord kept His anger against him.” The hermit went home, passed the night in prayer, and went again to the tomb, when Rodrigo said, “They eat me now, they eat me now, I feel the adder's bite.” So his sin was atoned for, and he died.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Rodrigo from Fact Monster: