Ekadashi In Vachanamrut Gadhada II. 8. Bhagwan Swaminarayan has related the story of Ekadashi: "Once Bhagwan Narayan was resting. A demon named Murdanav came and challenged Him to a duel. Suddenly a damsel appeared, evolved out of the Ekadash indriyas of God. [The ten indriyas (sense organs) comprise the five karma indriyas (mouth, hands, feet, anus and genital organs) and five gnan indriyas (eyes, ears, nose, skin and tongue). The ten indriyas along with the mind are collectively known as Ekadash indriyas.] Murdanav was so attracted to this damsel that he asked her to marry him. The damsel agreed, but only if he agreed to a duel with her, "Whoever shall defeat me shall marry me." Blinded by passion, he fought with her. The damsel killed him. Pleased with her, God granted her a boon. She asked, "O Prabhu! As I have manifested from your Ekadash indriyas, let my name be Ekadashi. I am wedded to tap (austerity) and I desire that people should observe the Ekadashi vrat (fast) and control their Ekadash indriyas on this day. Bhagwan Narayan agreed." Ever since, Hindus fast on the eleventh day of sud (shukla) paksha and vad paksha of the month. http://www.swaminarayan.org/calendar/2008/ekadashi.htm