The king who had everything but one thing
King Mahijita of Mahishmati was a ruler in whom the shastra could find no fault. His kingdom was prosperous, his treasury full, his praja without complaint, his queens virtuous and devoted. Yet the one thing that gives a king rest — a son — had been denied him. He had performed shata-yajna, given daan of a hundred cows a day for ten years, bathed at every tirtha of Bharatavarsha; still the palace nursery stood empty.
The council of rishis
In quiet desperation Mahijita assembled the sixteen greatest rishis of his kingdom in the palace sabha, seated them upon deer-skins, and folded his hands. 'Maharshis,' he said, 'I have followed dharma without deviation. I have given without counting. Why does the greatest of blessings pass over my house? If there is a fault, name it — and if there is a remedy, prescribe it.' The rishis conferred in silence and turned their gaze upon Rishi Lomash, the eldest, whose tapa-drishti reached across janmas.
Rishi Lomash
Lomash closed his eyes and travelled backward through the king's lives. He said at last, 'Rajan, in your immediately previous birth you were a poor merchant on the Deccan roads. On one Jyeshtha noon, upon a Shravana Krishna Ekadashi, a thirsty cow came to your well and lowered her head; you, hard-pressed for water yourself, drove her away with a stick. The cow died within sight of your house. That one papa — small in a merchant's life — has been blocking your santan-yog through this whole royal birth. The remedy is the Putrada Ekadashi of Shravana Shukla that approaches; you and your queen must observe it together with the katha itself heard from a Brahmin.'
The birth of the heir
The king and his chief queen observed the vrat exactly as Lomash prescribed: nirjala fast the whole day, jagran through the night with Vishnu Sahasranama, and the katha of Putrada heard from Lomash's own lips before Dwadashi parana. Within that same year a strong, dharma-loving son was born to them, whom Lomash named at the naam-karan and blessed to rule after his father. Since that day the vrat has been the traditional Vaishnava remedy for every couple seeking children, and for every parent seeking the wellbeing of children already born.
"Grants virtuous progeny to childless couples, and is also observed for the well-being, health, and dharma-shraddha of existing children. Especially recommended for couples where past-life karma is suspected as the obstacle."