It is one of the most ancient fasts, and finds mention in the Puranas. It is believed to be one of the most auspicious days of the entire year. According to the Bhavishya Purana, when men bathe the snakes called Vasuki, Takshaka, Kaliya, Manibhadra, Airavata, Dhritarashtra, Karkotaka and Dhananjaya with milk on the fifth day of the bright fortnight of Shriven, they ensure freedom from danger for their families. In some parts of southern India, figures of snakes are drawn with red sandalwood paste on wooden boards, or clay images of snakes coloured yellow or black are purchased. These are then worshipped and offered milk.
Snake charmers wander about with all sorts of snakes, to which people offer milk.
The snake charmers are paid some money for allowing this Serpent worship developed gradually from the fear of serpents that must have taken a heavy toll on life, particularly at the beginning of the rainy season. In the Ashvalayana Grihyasutra, the Paraskara Grihyasutra and other Grihyasutras, a rite called Sarpabali or 'offerings to serpents' was performed on the full moon night of Shriven. However the reason that it was moved from the full moon night to that of the fifth night of the bright fortnight is not apparent. It may be due to the slight change in the time of the onset of the rains.