The Ekadashi vrat katha told as the beginning of all Ekadashis is the story of Utpanna, "the one who was born": when the demon Mura came to kill Vishnu as he slept in a cave at Badrikashram, a shining maiden rose from Vishnu's own body and defeated him. Vishnu named her Ekadashi, because she appeared on the eleventh day of the lunar fortnight, and promised that whoever fasts on her day would be dear to him.
The next Ekadashi, its tithi, the Smarta and Vaishnava days and the parana window for your city are on the Ekadashi vrat dates page. This page is only the story, told in our own words.
The story of Utpanna Ekadashi
Long ago, in the age of truth, there lived a demon named Mura. He was the son of an earlier tyrant and had grown so strong that he drove Indra and all the gods out of heaven. The gods wandered the earth without a home, and in the end they went together to Shiva and asked for help. Shiva told them that only Vishnu could face this enemy, and sent them on to the ocean of milk.
Vishnu heard them out and rose to fight. He went to Mura's city, Chandravati, and battled the demon and his army. The war went on for a very long time; in the vrat books it lasts a thousand years of the gods. Mura's soldiers fell in their thousands, but Mura himself would not give in.
At last Vishnu, tired, withdrew from the field. He went north to Badrikashram in the Himalaya and entered a cave called Himavati, which had only one opening. There he lay down to rest, and fell into the deep sleep that the stories call yoganidra.
Mura followed him. He found the cave, saw Vishnu lying still, and thought that the moment had come to kill him. He raised his weapon.
At that instant a maiden stepped out of Vishnu's body. She was radiant, armed, and full of his strength. Mura was astonished and turned on her instead. They fought, and in the story she defeated him with a single sound, a "hum" that turned him to ash; in other tellings she struck him down in battle.
When Vishnu woke, the demon was gone and the maiden stood before him with her hands joined. He asked who she was. She said she had been born from him to protect him while he slept. Vishnu was pleased and asked her to choose a boon.
She asked that those who fast on her day be freed from their faults and reach his abode; that they be given good health and a steady mind; and that she be the most loved of all the vows. Vishnu granted all of it. Because she had appeared on the eleventh tithi, he named her Ekadashi, and said that from then on the eleventh day of each fortnight would be hers, and whoever kept it with devotion would be kept by him.
That day, in the dark half of Margashirsha (Kartika in the amanta reckoning), is remembered as Utpanna Ekadashi, the day she was born.
Reading the story calmly
Like many Purana stories, this one has a war and a demon reduced to ash. It is not a story about fear or about enemies outside the house. Teachers in the Vaishnava tradition often read Mura as the restlessness that attacks a person when their guard is down, and the maiden as the steadiness that rises from within when one rests in God. The promises Vishnu makes are a blessing, not a bargain, and nobody is lessened for being unable to fast.
Every Ekadashi has its own katha
The year has twenty-four Ekadashis, two in each lunar month, and two more, Padmini and Parama, in a year with an extra month (adhik maas). Each has its own name and its own story. In the vrat books they are framed as a conversation in which Yudhishthira asks Krishna about the Ekadashi of a particular month, and Krishna replies with a tale, often one first told by a sage to a king.
So the story of Rama Ekadashi, in Kartika, tells of a princess named Chandrabhaga and her husband, while Kamada Ekadashi, in Chaitra, tells of a gandharva couple separated by a curse. Some families read only the story of the day's Ekadashi; others read the Utpanna story first, as the root, and then the day's own katha. Dev Uthani Ekadashi, when Vishnu wakes from his four months' sleep, is kept with its own songs and customs.
Smarta and Vaishnava days
Most fortnights everyone fasts on the same day. Sometimes the calendars differ. The Smarta rule, followed by many households, keeps the fast on the day Ekadashi prevails at sunrise. Many Vaishnava communities, including ISKCON and those following the Gaudiya and Pushti traditions, look more strictly at the moments before dawn: if Dashami, the tenth tithi, is still running then, they move the fast to the next day. Neither is wrong; each follows its own lineage. The Ekadashi page shows both days when they differ.
How the katha is heard
The story is read during the Vishnu puja of the day, after the tulsi leaves and the lamp have been offered, or in the evening when the family sits together. In many homes an elder reads it from a small Ekadashi mahatmya book, and children are asked to remember the name of the day's Ekadashi. Those who keep night jagran often read it again late in the night between bhajans.
How to keep the fast itself, from the Dashami evening meal to parana on Dwadashi, is on the Ekadashi puja vidhi page.
What the story carries today
For people who keep every Ekadashi, Utpanna is a kind of birthday, and many begin the lifelong vow on that day. The story also explains something about the fast: it is not punishment of the body but a resting in Vishnu, the way he rested in the cave while something born of him kept watch. Twice a month, the fast asks for a lighter plate and a quieter day.
If you keep Ekadashi through the year, the Satyanarayan katha is another Vishnu story many families read, often on Purnima. The panchang for your city shows when Ekadashi begins and ends on any day.