Saphala Ekadasi vrat falls in Krishna Paksha of Paush Month in North Indian calendars and in Margashirsha Month of Marathi, Gujarati, Telugu & Kannada calendars.
Here is the story of Saphala Ekadasi Vrat…
Once there lived a great and powerful king by the name of Mahishmatha. He had four sons. The eldest was called Lumpaka. Lumapaka was arrogant and was indulging all the possible bad deeds that a person should not do. He was not even refraining himself from hurting people. He used to punish common people and enjoy.
The king saw this for a long time and warned Lumpaka to change his behaviour. After few warnings also Lumpaka did not change. As per dharma Lumpaka was supposed to be given a death sentence but King Mahishmatha could not kill his son and so ordered him to leave the kindom. Lumpaka was exiled from the kingdom.
Lumpaka started to live in a forest outside the kingdom. Exiling him did not change the behavior of Lumpaka. He was still the same. Once there was a very cold winter and Lumpaka was finding it very difficult to find food. Lumpaka began very weak and soon his health detoriated. He fell ill and was unconscious for two days.
He woke up on the day of Saphala Ekadasi. Because of his weakness he was not in a position to hunt so was not able to get any food. There was a idol of Lord Vishnu at he place he fell unconscious. He saw the idol and prayed to Lord Vishnu for his fast recovery. He offered the fruits that fell on the ground to Lord Vishnu.
Lumpaka was not able to get any food was fasting the whole day and as he did not have enough food was not able to sleep the whole night.
Lumpaka has actually performed the Ekadasi Vrat of fasting for the whole day and keeping awake for the whole night. The virtue of performing the Ekadasi Vrat is very high and removes all the sin. Observing the Ekadasi Vrat would fetch wealth and prosperity.
By virtue of the Saphala Ekadasi Vrat Lumpaka observed that his energy was renewed. His sins were washed off and his thought process was also changed. Now Lumpaka became a completely different person. A person who would respect elders, follow the Dharmas, love others etc.
Suddenly there was a voice from the sky which said that Lumpaka was freed from all the sins and that he should return to his father and rule the kingdom.
As soon as Lumpaka reached his kingdom, he saw that Mahishmatha was there to welcome him. He was astonished and was eager to know how his father knew that he was coming.
Mahishmatha replied that Lord Vishnu had come in his dream last night and said that Lumpaka would return to the kingdom. The lord also said that Lumpaka was changed and should be welcomed. He ruled the kingdom after his father following all the dharmas and was applauded by one and all.
Thus by observing the Saphala Ekadasi Vrat Lumpaka was able to change his fortune and himself.
By observing Saphala Ekadasi one would get back all that is lost and much more like health, wealth, belongings, affection, honor etc.