Once there was a moneylender in a village who had two daughters. Both sisters used to observe fast on Purnima. However, both had different views on fasting. The elder sister was very pious and religious and used to observe Sharad Poonam fast with full devotion. She used to break her fast after giving Arghya to God Moon in the evening and never used to break her fast without completing it. On the other hand, the younger sister was never very keen in observing the fast but used to observe it for namesake. She used to break her fast without completing it.
When they grew up, both sisters were married. The elder sister gave birth to healthy children. But, the younger sister had no child. All her babies died as soon as they were born. The younger sister was very depressed and to find a remedy for her sorrows she visited a saint and shared her misfortune. The saint understood the reason of her sorrows and misfortune and told her that she had been observing Purnima fasts without any interest and devotion and due to which she has brought misfortune to herself. The saint advised her that if she observes the fast with full devotion and dedication her bad time would be over by the grace of God Moon.
The younger sister realized her mistake and observed the next Sharad Purnima fast with full devotion and rituals. After her penance and ritualistic fasting on Purnima, she gave birth to a child but unfortunately, this child too died immediately after birth.
The younger sister knew that her elder sister has the blessing of Lord Moon and she might have the power to make her child alive again. Hence, the younger sister made a plan and laid down the dead body of his child on a small bed and covered it with a cloth. She then called her elder sister to her home and offered her to sit on the same bed on which the dead body of the baby was lying. As the elder sister was about to sit on the bed, her clothes touched the dead baby and the baby came back to life and started crying. The elder sister was surprised and scolded her younger sister for being so careless. The younger sister then told her elder sister that the baby had died at birth and the baby came to life again by her elder sister’s touch. This effect was none other than due the grace of God Moon and the power of Purnima Vrat.
Since that day, tradition of observing the fast on Sharad Purnima started. Gradually, the Sharad Purnima fast became popular and people started observing it with full rituals.