from the Bhavisottara Purana
When: During the waning moon in the month of March/April
The glories of Papamocani Ekadasi is described in Bhavisottara Purana in the conversation between Lord Krishna and Maharaj Yudhisthira.
Once Maharaj Yudhisthira asked Lord Krishna my dear Lord Krishna you have already explained the glories of Amalaki Ekadasi now please describe the Ekadasi which occurs during the waning moon in the month of March/April. What is the name of this Ekadasi? Also describe to me the procedure for observing this Ekadasi and its results. Lord Krishna replied, O best of Kings! The name of this Ekadasi is Papamocani. Now please hear its glories as I describe to you. Long long ago the glories of this Ekadasi was spoken by the Sage Lomasa to King Mandata. This Ekadasi takes away all ones sinful reactions, destroys ones ghostly condition of life and awards one eight kinds of mystic perfections.
Sage Lomasa said, 'In the ancient time Kubera the treasurer of the demigods had a beautiful forest of flowers called Caitraratha where the weather was pleasant as a result of ever (spring?) The heavenly dancing girls such as gandharvas and kinnaras enjoyed various sports there. Demigods headed by Indra used to come there and enjoyed various exchanges. In that forest a great sage named Medhavi who was a staunch devotee of Lord Shiva was engaged in performing austerity. The Apsaras or the heavenly dancing girls tried to disturb the sage in various ways. Among the Apsaras one famous Apsara named Manju Ghosa devised a means to captivate the mind of the sage. Due to fear of the sage Manju Ghosa built a cottage a little away from the ashrama of the sage and began to sing in a sweet voice accompanied with the musical instrument Bina. On seeing Manju Ghosa who applied sandal wood pulp on her body wore a fragrant flower garland and was engaged in singing sweetly, even the cupid who is an enemy of Lord Shiva tried to conquer the sage who was the devotee of Lord Shiva. Since Lord Shiva burnt the cupid to ashes therefore remembering his previous enmity the cupid, in order to take revenge entered in to the body of the sage. At that time sage Medhavi who wore a white sacred thread on his body and lived in the ashrama of Chyavana Risi appeared as the second cupid. The lusty Manju Ghosa slowly came before the sage. The sage Medhavi also became overwhelmed by lust and forgot his worshipable lord. He gave up the practice of devotional service and became so much intoxicated in relishing the association of the women that he even lost the sense of discriminating between day and night. In this way sage Medhavi spend many years in enjoying lusty activities.
Thereafter when Manju Ghosa saw that the sage has fallen down from his position she decided to return to the heavenly planet. She said to sage Medhavi who was engaged in conjugal affair 'O great sage! now please give me permission so that I can return home. Then sage Medhavi replied O beautiful women! You have come to me only in the evening stay here tonight and you can return in the morning. On hearing these words of the sage Manju Ghosa became frightened and continued to live with him for a few more years. In this way although Manju Ghosa lived with a sage for fifty seven years nine months and three days yet it appeared to be only half of a night to the sage. Then Manju Ghosa again asked for the permission from the sage to return home but the sage said O beautiful one! Please hear my words. This is only morning, please wait till I finish my morning rituals. Then the apsara smiled and said to the sage with amazement. O great sage! How long it will take to complete your morning rituals? Has it not finished yet? You have spent many years in enjoying my association. Therefore please consider the actual value of the time. On hearing the words of the apsara the sage came to his senses and after carefully calculating the time he said Alas! O beautiful one! I have simply wasted long fifty-seven years of my valuable time. You have ruined everything and spoiled all my austerities. The eyes of the sage filled with tears and his entire body began to tremble. Sage Medhavi cursed Manju Ghosa in the following words 'You have behaved with me like a witch therefore you will immediately become a witch. O sinful unchaste Lady! shame on you.
After being cursed by the sage in this way Manju Ghosa humbly said to the sage, O best of the brahmins! Please withdraw your heavy curse. I have spent many years in your company O my lord for this reason I am a fit candidate for your forgiveness, please be merciful to me. The sage replied, O gentle lady! what will I do now ? You have destroyed my entire wealth of austerity, still I am telling you the procedure from getting freed from this curse. The Ekadasi which occurs during the waning moon in the month of March/April which called Papamocani and is capable of distroying all ones sinful reactions. If you follow this Ekadasi strictly and faithfully then your ghostly condition of life will be vanquished. After speaking these words sage Medhavi returned to the ashrama of his father sage Chyavana. As soon as sage Chyavana saw his fallen son he became extremely unhappy and said, 'Alas! Alas! O my son what have you done? You have ruined yourself. You should not have spoiled your entire treasury of austerity simply being captivated by an ordinary lady sage Medhavi replied O respected father! Due to misfortune I have committed great sins in the association of an apsara. Therefore please instruct me regarding the atonement of my sinful reactions. On hearing the pathetic words of his repentant son sage chyavana said O my son! by observing Papamocani Ekadasi which falls during the waning moon in the month of March/ April all ones sinful reactions are completely distroyed. Therefore you should observe this Ekadasi. On hearing these kind words of his father sage Medhavi exhibited special enthusiasam in observing this Ekadasi. By the influence of this Ekadasi all the sinful reactions of sage Medhavi were destroyed and he became a very pious. Meanwhile Manju Ghosa also observed this auspicious papamocani Ekadasi and became liberated from the ghostly condition of life. She then regained her divine form and return to heaven.
After narrating this story to king Mandata sage Lomosa concluded as follows. My dear king just by observing this Papamocani Ekadasi all ones sinful reaction are automatically destroyed. By hearing or reading the glories of this Ekadasi one achieves the result of donating one thousand cows. By observing this Ekadasi all kinds of sinful reactions resulting from a killing a brahmin, killing an embryo, drinking wine and associating with ones guru's wife are totally uprooted. The purport is that since this sacred Ekadasi is all auspicious and destroyer of all sins everyone should strictly observe this Ekadasi.