The story of Nirjala Ekadashi is one of the most famous ones and involves the Pandavas. It is believed that Bhim, the mighty Pandava, wanted to keep a fast but couldn’t because of his appetite. He loved food and found it very difficult to fast, even on Ekadashi. While the rest of his family observed every Ekadashi with devotion, Bhim could not bear the idea of staying hungry, let alone thirsty.
But when he felt left out and guilty, he approached a sage to share his sadness about it. And then it was advised to Bhim that he should observe just one Ekadashi fast in a year, the Nirjala Ekadashi, as it has the power, merit, and blessings, of all 24 Ekadashis.