The kingdom without an heir
In Bhadravati by the river Godavari ruled King Suketuman, righteous and generous, whose queen Shaibya was famed for her devotion. But year after year no child came to them. The ministers murmured, the temples were kept lit day and night, every yajna the shastra prescribed for progeny was performed — nothing bore fruit. The king aged; grief entered his sabha and would not leave. At last, unable to bear the weight of the empty crown, Suketuman quietly left the palace one Pausha dawn, telling only his wife, and walked alone into the forests of his own kingdom to seek from any rishi he could find the reason for his misfortune.
Wandering to the Manasa-sarovara
For many days the king wandered, tasting no food, drinking only from streams, praying at every shrine he passed. His silks tore on brambles, his crown he left hanging on a peepal branch, until he looked no different from a mendicant. On the sixth day he came upon a beautiful kund where the Manasa-sarovara feeds a hidden stream, and around it he saw a circle of luminous rishis — the Vishwadevas themselves in ascetic form — seated in silent tapas. Falling at their feet, he wept out his whole grief without hiding a single thought.
The vrat of the Vishwadevas
The eldest Vishwadeva lifted the king's chin and said, 'Rajan, you have come on an auspicious day. Today is Pausha Shukla Ekadashi — the Putrada Ekadashi, which grants progeny to those to whom no other vrat has given a child. It is also the day upon which, in Vaikuntha, the northern gate of Bhagwan Vishnu's inner court stands open — the door which the shastra names as the very gate of moksha. Fast with us today. Keep jagran. At midnight bathe in this kund with Vishnu's name on your lips. At Dwadashi parana receive our blessing. Both what you seek here and what your soul secretly seeks beyond will be given.'
The vrat and the son
The king observed the vrat exactly as told. All day he fasted upon Ganga-tulsi jal; through the night he circled the kund reciting Vishnu Sahasranama with the rishis. At Dwadashi dawn he broke the fast on prasad offered by the Vishwadevas themselves. They said, 'Return, Rajan. Within the year your queen will bear a son who will surpass you in dharma.' Suketuman walked back to Bhadravati as one reborn. Shaibya received him with the news that a tejasvi son was already stirring in her womb — a son who would grow into a great dharma-raja.
The gate of Vaikuntha
Since then the same Ekadashi is observed in Tirupati, Srirangam and every great Vaishnava kshetra of the south as Vaikuntha Ekadashi — Vaikuntha-dvara-ekadashi. On this day alone, at Brahma-muhurta, the northern gate of the sanctum is opened and devotees walk through it in a single silent line; that darshan is said to grant liberation at the hour of death, no matter where the vrati dies. In the north the same day is called Putrada, and given to the vrat for progeny. Both are one — for the shastra declares that a righteous child is itself a door through which one's own pitrs walk to Vaikuntha.
"Grants virtuous progeny and simultaneously opens the gates of Vaikuntha. Considered by many acharyas the single most powerful Ekadashi for moksha: darshan through the Vaikuntha-dvara on this day is said to guarantee liberation at the hour of death."