Arjuna asked the Lord, 'O Janardana, what are the benefits of complete fasting, eating only supper, or eating but once at midday on Ekadashi, please tell me'.
Lord Krishna replied, 'O Arjuna, on the Ekadashi that occurs during the dark fortnight of the month of Margashirsha (November-December), one should begin a fast on Ekadashi. On Dashami, the day before Ekadashi, just as the Sun is about to set, he should eat supper.
The next morning he should make a vow, to observe fasting according to the rules and regulations. On the day of fasting the devotee should not speak to those who are fallen from their religious duties. He should respectfully worship Lord Govinda with first-class food, flowers, and so on. He should also avoid sleeping during daytime and completely abstain from sex. Fasting from all food and water, he should joyfully sing and hear the Lord's glories for His pleasure throughout the night. One should never discriminate between the Ekadashis that occur during dark and bright fortnights.
A person who feeds just one brahmachari earns ten times more merit than one who feeds ten brahmanas in his own house. O son of Kunti, all the forefathers and demigods in heaven become very satisfied when one gives food grains in charity. But the merit one obtains by observing a complete fast on Ekadashi cannot be measured.
One should therefore observe fasting on Ekadashi either by eating only once at midday, abstaining from grains and beans; or by fasting completely. Anyone afraid of the miseries of material existence should observe Ekadashi.
Ekadashi is the most purifying of all days.
Utpanna Ekadashi Fast Story
In ancient times, there once lived a fearsome demon called Mura. He terrified all the demigods, defeating even Indra, Vivasvan, the sun-god; the eight Vasus; Lord Brahma; Vayu. the wind-god; and Agni, the fire-god. With his terrible power he brought them all under his control.
Lord Indra then prayed to Lord Shiva. “O Shiva, we are all suffering the atrocities of Mura and spending our life in Mrityu Loka. Please tell us a way to come out of this problem.” He suggested him to approach Lord Vishnu. All the devatas appealed to Lord Vishnu for solving their problem.
Lord Vishnu asked about the monster, and Indra said, “the monster has its origin from Brahmna Vansh and his name is Mura and he lives in the city of Chandravati.”
Upon hearing this, Lord Vishnu assured them that he will kill the monster and save their lives. Lord Vishnu went along with them to Chandravati. At that time, the demon Mura was marching along with the other demons, for a war. When they saw the devatas, they began fighting with them.
The demons used their weapons on Lord Vishnu. The weapons employed by Lord Vishnu to kill Mura were converted to flowers, by the power of Mura. The battle went on for many years, but Mura could not be defeated.
Finally, Lord Vishnu went to a cave in Badarikashrama to take rest. Mura too came there to kill Lord Vishnu. At which time, an attractive girl appeared in the cave and started fighting with Mura. She knocked him unconscious and cut off his head. When Lord Vishnu woke up, he saw that someone had killed the monster. The girl told him that the demon was going to kill him and so she had originated from Lord Vishnu’s body and killed him. Lord Vishnu named her Ekadashi as she was born on the day of Ekadashi.
This year, Utpanna Ekadashi falls on December 03, 2018.