The story of Annada Ekadashi is one which tells us of the famous king Harishchandra who fasted on the day of Annada Ekadashi. The king was a man of integrity and truth but had lost his kingdom as well as his queen and his son. He then becomes a guard that was employed by a dog-eater to look after a crematorium. Although he has gone from a king to a lowly servant, Harishchandra did not lose the qualities that made him a great man.
One fateful day, Harishchandra met a sage named Gautama Muni. The sage took pity on him after hearing of his plight and gave him instructions on how to fast to gain purification of his soul. He told the king about the month of Bhadrapada when an Ekadashi called Annada takes place.
This auspicious Ekadashi was known to purify and wash away all the sins of a man. Gautama Muni beseeched King Harishchandra to fast on that day so that good fortune would return to him once again.
Once the sage left, the king began to prepare for his fast. On the day of the Ekadashi, he fasted and to much amazement, he found that he was absolved of all his sins. His misery and sorrow left him and he felt like a new man. Needless to say, he was reunited with his wife and son and regained his kingdom as well. Therefore, it is believed that anyone who fasts on the day of Annada Ekadashi is freed from his sins and is granted permission to enter the heavenly spiritual world.