Once, the deities went to sage Kashyapa after being tormented by the demons. They complained to him about the misdeeds of the demons, who also happened to be their step brothers. Sage Kashyapa became extremely furious, when he heard about the misdeeds of his sons – the demons. To protect the deities from his sons, he commenced a penance to please lord Shiva.
Lord Shiva became very pleased by his penance and appeared before him. He asked Kashyapa to demand anything he wished. Kashyapa then requested Lord Shiva to take birth as his son and destroy the demons. Lord Shiva blessed him and said – ‘So be it’.
Lord Shiva, later on took birth as eleven Rudras from the womb of his wife Surabhi. The name of these eleven rudras were as follows:-
1) Kapali, 2) Pingal, 3) Bheem, 4) Virupaksha, 5) Vilohit, 6) Shastra, 7) Ajapad, 8)Ahirbudhnya,
9) Shambhu, 10) Chand and 11) Bhav.
These eleven Rudras fought battles with the demons and killed them. The deities were relieved after the death of the demons. They worshipped these eleven rudras to express their gratitude and indebtedness.