Story crows and the greatness of Shiva Panchakshari Mantra
is found in the Shiva Purana. Long ago, the King of Kashi had a daughter named
Kalavati. She was an ardent devotee of Shiva and received Shiva Panchakshari Mantra (Om Namah Shivaya) at a very young age.
Years later she married, Dasarha, King of Mathura. When he
touched Kalavati he experienced unbearable heat.
Kalavati said that it was because of the sins committed by
the king.
Therefore, she took King Dasraha to Sage Garga.
Sage Garga purified the sins of Dasarha by mantras. The he
asked to king to stand in a river.
When the king stood in the river, sins came out of his body
in the shape of crows. Many of them flew away and soon fell down with their wings
burnt.
Sage Garga told the king that the crows were the volume of sins
accumulated by the king during several births.
The king thus got purified of his sins and attained moksha.