Ekadashi of Vaishak Shukla Paksha is known as Mohini Ekadashi., Observing a fast for Lord Vishnu today, one gets freedom from all kinds of attachment and progresses in spiritual life. According to the scriptures, Gods and demons churned the milky ocean in ancient times. When the nectar came out of this churning, a war broke out between the Gods and demons, since each one wanted it for themselves. Then Lord Vishnu incarnated on this date in the form of Mohini and diverted the demons as they were easily distracted by a beautiful female form.In the pretext of dividing the nectar , the elixir was consumed by the Gods.
Krishna himself had told Arjuna the importance of this Ekadashi .According to Padma Purana, Yudhishthira asked Krishna, “Lord! What is the importance and significance of the Vaishakh Shukla Ekadashi ? Then Shri Krishna said that Mohini Ekadashi is the Ekadashi of the Shukla Paksha of Vaishakha Masa. This is considered to be the destroyer of all sins. On this day worshiping Vishnu will liberate a devotee from the temptation of the world.
On this day, meditate on Vishnu, and resolve for the fast. After this, take a bath and worship Lord Sri Krishna with shodasopachara (sixteen upacharas include bath, sandal paste, lamp, dhoop, arati, naivedya etc). Do not sleep during daytime and preferably do not sleep at night.
The next day, i.e, on the 16th of May, Thursday morning, invite Brahmans and give them gifts and dakshina. Arrange food for them. After Brahmans had their food, we can eat ourselves.
Story glorifying Mohini Ekadashi fast
There is a town of Bhadravati on the banks of Saraswati river. There the king by name of Dhritiman was ruling. There was a Merchant in the same town, named Dhanapal. He was a great devotee of Lord Vishnu and was very virtuous. He had five sons- Sumanas, Dwitiman, Medhavi, Sukta and Dhritabuddhi. The last son spent his father’s money in vices and committed many acts of sin.
One day his father turned him out of the house. Wandering here and there, overcome by hunger and thirst, he reached the ashram of Maharishi Koundinya. He bowed to the sage and prayed ‘Please show mercy on me and give me advice on such a fast, which will lead to my salvation.’ Then Maharishi Koundinya told him about Mohini Ekadashi of the Vaishak Shukla paksha. Dhritabuddhi observed the fast with devotion and being granted a divine body, sat on Garuda and went to Shri Vaikuntha .