Shitala Satam Vrat Katha, Story of Sheetala Saptami is given here. Shitala Satam is observed in Shravan Month as per Gujarati calendar. Skanda Purana describes the iconography of Goddess Shitala Mata.
Shitala Mata Vrat katha is mentioned in Bhavishyottara Purana. This story is associated with the legend of Indralumna, the King of Hastinapur. Name of his wife was Pramila who had great faith in performing religious ceremonies. And Indralumna’s son was Mahadharma and daughter was Shubhakari whose husband is Prince Gunvan.
One year of married life passed happily. When Gunvan went to his in-laws house to fetch his wife, Indralumna asked him to stay over for a couple of days as the next day Shubhakari had to observe Shitala Mata Vrat. Gunvan accepted it.
On the day of Shitala Mata Vrata, Shubhakari went to a lake with her friends to perform Shitala Mata Vrat. But they lost their way in between. Then an old woman came and guided them towards the lake. After reaching the lake, Shubhakari performed the holy bath and observed the vrat.
The old woman was herself Goddess Shitala Mata and she got pleased with the puja of Shubhakari. The goddess asked the princess to state any wish, but Shubhakari told that she would ask it if there is any need.
After the Puja, Shubhakari and her friends wanted to offer some charities to the Brahmin and his wife. There they got know about the death of the Brahmin due to the snake bite. Then Shubhakari asked Shitala Mata a wish to restore the life of the Brahmin. And with the blessings of Shitala Mata, Brahmin got alive and thanked Shubhakari and prayed to the Goddess.
Since then, the people of Hastinapur started performing ‘Shitala Satam Vrat and Puja’.