Navami

The ninth lunar day (navami) is associated with Vetrasura and his death at the hands of the goddess Gayatri devi.

(The name Vetrasura does not occur in any other Purana and seems to be a concoction of the Varaha Purana.)

In an earlier life, Vetrasura’s father had been killed by Indra with foam, as he had obtained a boon that could not be killed by anything else. (Although the name of Vetrasura’s father is not given, the foam identifies him as the famous demon Vritra. Let us therefore call him Vritra.)

In this next birth, Vritra remembered what had happened in his earlier birth. He meditated so that he might obtain a son who would kill Indra. The river Vetravati came to Vritra in the form of a woman. She married Vritra and out of this union was born Vetrasura. Vetrasura became a powerful enemy of the gods.