Once he saw a cow grazing in the paddy field and he drove her away by throwing Darbha (sharp, pointed grass). The slender cow died by this. It was Jaya - Parvati's friend, who had taken the form of a cow. This news upset the Rishis and they refused to luncheon at his Ashram. Gautama requested Rishis to show a way out of this sin. He was advised to approach Lord Shiva and request him to release Ganges and a bath in the Ganges would set him free of his sins.