Kaleyas Ally with Vritra to Threaten the Gods
The Kaleyas, terrible danavas invincible in battle, arm themselves and place themselves under Vritra, pursuing the gods led by Indra everywhere. The thirty gods, with Indra at their head, approach Brahma for a means to kill Vritra. Brahma tells them: go to Dadhicha. Ask for his bones. Fashion the vajra. With it, Indra will kill Vritra.
Lomasha said: "O king! O great king! Then listen to his divine, extraordinary and superhuman account — Agastya's powers and his infinite soul."
In the Krita yuga, there were terrible danavas, invincible in battle. Masses of them, known as the Kaleyas, and they were extremely terrible. They armed themselves with many upraised weapons and placed themselves under Vritra. They pursued the gods everywhere — the gods led by the great Indra.
In ancient times, the thirty gods decided to act so that Vritra might be killed. Placing Purandara at the forefront, they approached Brahma.
Brahma saw them all, their hands joined in salutation, and said: "O gods! I know the task that all of you wish to undertake. I will tell you the means whereby you can ensure Vritra's killing. There is a famous, great and wise rishi by the name of Dadhicha. Together, go to him and ask him for a boon. The one with dharma in his soul and virtue in his mind will happily grant it to you. If you wish for victory, all of you must tell him these words: 'For the welfare of the three worlds, give us your bones.' He will give up his body and give his bones to you. With those bones, fashion the firm and greatly terrible vajra. It will be large, capable of killing enemies. It will be sharp and will have six sides. It will make a terrible sound. With that vajra, Shatakratu will kill Vritra. I have told you everything. Do this without delay."
Having been thus addressed, the gods took their leave of the grandfather. Aranyaka Parva, Chapter 395