Significance and legend
In the Kurma and Bhavishyottara Purana traditions, Krishna recounts that Lord Rama asked the sage Vasishtha for a vrata to relieve his grief at separation from Sita. Vasishtha described the Ekadashi of the bright half of Vaishakha with the story of Dhrishtabuddhi. In the city of Bhadravati on the Sarasvati river, the pious merchant Dhanapala had five sons. The youngest, Dhrishtabuddhi, wasted the family wealth on gambling and evil company and was eventually cast out of the house. Wandering hungry and tormented, he came by chance to the ashram of the sage Kaundinya, who had just bathed in the Ganga.
Drops of water from the sage's garments fell on Dhrishtabuddhi, and his mind cleared. He begged for a way to atone for his sins, and Kaundinya told him to observe Mohini Ekadashi. He did so with sincerity, was purified, and at the end of his life attained Vishnu's abode. The Ekadashi is also associated with the day Vishnu took the enchanting form of Mohini to distribute the nectar of immortality to the gods, and its name is understood as the one that cuts through moha, delusion.
How Mohini Ekadashi is observed
Devotees take a sattvic meal on Dashami and fast on Ekadashi, worshipping Vishnu with tulsi, sandal and flowers. In some temples the Lord is adorned as Mohini. The day is spent chanting Vishnu's names, reading the Vishnu Purana or Bhagavata, and keeping a night vigil. Charity of water, fans and food is especially appropriate in the summer heat. The fast is broken on Dwadashi after sunrise during the parana period, avoiding Hari Vasara, with food first offered to Vishnu.