Narada's descent into the sabha
One autumn morning in Mahishmati, as King Indrasena of the Ikshvaku line held his open court, the veena of Devarshi Narada was heard above the palace. The whole sabha rose. Narada descended, took the seat of honour, accepted the arghya, and said with the gravity he rarely used: 'Rajan, I have just returned from Yamalok. Amid the pitrs I saw your late father. He has been detained for a single unfulfilled Ekadashi vrat from the last year of his life, and asks — if his son loves him — that Indira Ekadashi of Ashwina Krishna Paksha be observed in his name.'
The vidhi
The king, weeping openly before his sabha, folded his hands and asked how. Narada said, 'On Dashami perform pitru shraddha with pinda and Brahmin bhojan; sleep on the floor with a single cloth. On Ekadashi fast completely — no water if you can bear it — bathe in a nearby tirtha at brahma-muhurat, and pass the whole night in jagran chanting Vishnu Sahasranama and the thousand names of Vaikuntha. On Dwadashi parana feed Brahmins first with your own hands, then place a copper vessel of water and til into the palms of the eldest Brahmin, and give every particle of the vrat's punya as pitru-arpan to your father.'
The king's observance
Indrasena observed the vrat exactly as Narada prescribed. Through the fasting day and the night of jagran he did not once let his mind stray from the image of his father as he had last seen him — tired, kind, laying a hand on his son's head. At Dwadashi parana he fed a thousand Brahmins with his own hands, gave the sankalpa-jal with til, and dedicated every kana of the punya to his pitr.
The father's ascent
As the last sankalpa-jal fell, in the distant halls of Yamaloka a bright vimana descended. Yama himself rose from his seat and personally led Indrasena's father out of the shadow. The old king, freed of every kana of his karma, ascended straight to Vishnu-loka. Narada returned to the sabha the same evening to confirm the deliverance: 'Rajan, your single Indira vrat has done what a hundred shraddhas could not. From today, in Pitru Paksha every son of Bharata who observes this vrat in the name of his pitrs shall achieve the same.'
"The supreme pitru-tarpan Ekadashi of the year. Redeems ancestors trapped in lower yonis or delayed in Yamaloka and grants them direct passage to Vishnu-loka. Prescribed once in every son's lifetime for the ascent of the pitrs."