At the beginning of the material worlds creation the Supreme Lord Hari created the moving and non-moving living entities within this world made of five gross material elements, simultaneously for punishing the sinful persons Lord created a personality whose form was the embodiment of sins the Sanskrit word is Papapurusha. The different limbs of this personality were constructed of various sinful activities, his complexion is black and the colour of his eyes is yellow. He inflicts extreme misery upon sinful person.
The Supreme Lord Hari who is the giver of happiness and distresses glorified with nice prayers then had Him sit upon the golden thrown. The Supreme Lord heard the loud crying sound from the southern side He asked Yamraj to know the fact. Yamraj replied,”O Lord! The different living entities of the planetary system have fallen into the hellish region. They are suffering extremely for their misdeeds. The horrible crying sound is because of suffering from the inflictions of their past bad karma(action).”
After hearing the reason of the loud crying sound from Yamraj Lord went to the hellish region of the south where the inhabitants were crying loudly, after seeing the Lord they began to cry even louder. The Supreme Lord’s heart became filled with compassion. Lord thought,”I have created all this progeny, and it is because of Me they are suffering.”After as Lord is always very merciful He suddenly manifested from His Own form the personality of the lunar day Shri Ekadashi.After that the different sinful living entities began to follow the vow of Ekadashi and were then elevated quickly to the abode of Lord Hari.So the lunar day of Ekadashi is the selfsame form of the Lord. The vow of Ekadashi is the utmost pious activity and is situated as the head among all vows.
Following the vow of Ekadashi, that personality who is the form all kinds of sinful activities gradually saw the influence of the Ekadadhi had so the Papapurush approached the Supreme Lord with doubts in his heart, he said,” I am Your created progeny and it is through me You wanted distress given to the living entities those who are very sinful. But now by the influence of the Ekadashi vow, I have become all but destroyed. Out of fear of Ekadashi I have tried to take shelter in every possible places but I cannot find a place where I can be free from the fear of Shri Ekadashi. Oh my Master! I am a product of Your creation, You are very merciful so kindly direct a place for me where I can reside feerlesly.”The Supreme Lord after observing the condition of Papapurush He laughed and told, “don’t lament any longer and listen, on the day of Ekadashi which is benefactor of the three worlds, you can take shelter of foodstuff in the form of grains. There is no reason to worry about this anymore, because My form of Ekadashi will no longer impede you.”
Therefore those persons who are seriously try for the ultimate benefit for the soul will never eat grains on the day of Ekadashi. According to the instructions of the Supreme Lord, every kind of sinful activity can be found in this material world takes shelter in this place od foodstuff(grains).
The Deity of Shri Ekadashi.
In the Satya Yuga once there lived a very fearsome demon called Mura,he terrified all the demigods, even he defeated the king of heaven Indra and by his terrible power he brought all of them under his control.All the demigods approached the Supreme Lord. When Lord came to know about the demon Mura Lord became very angry and immediately ordered all of them to attack Mura’s capital city Chandravati,all together and the Supreme Lord was leading them.Then there was a very big fight, the Supreme Lord faught with the demon for one thousand celestial years, for some rest Lord entered a beautiful cave named Himavati in Badrikashram. The demon was following the Lord so he also reached there. Seeing the Lord is sleeping he thought himself of killing Him.By the time Mura was planning, from the body of the Lord there manifested a beautiful young girl, who had a very bright complexion and equipped with various weapons. Being challenged by the goddess Mura preapared himself for fighting. Suddenly that effulgent goddess shattered Mura’s all the weapons and deprived him off his chariot also cut down his head brilliantly.
When the Supreme Lord wake up He saw the dead Mura and He also saw the beautiful goddess offering obeiscence to Lord,being pleased by the goddess Lord asked her for boon. The goddess prayed Him then told,” please give me the power to deliver those persons who will follow the vow of the Ekadashi day will be blessed by You and will get the religious attitude,wealth and liberation. “Lord was so pleased that He granted everything to the goddess and said,”you are My transcendental potency, have appeared on the eleventh day of the wanning moon so your name will be Shri Ekadashi. The person who will follow the vow of Ekadashi, Ishall burn up all his sins and bestow upon him My blessings and My transcendental abode.
(from Srila Vyasdev answering to the questions of Sage Jaimini).