Indra, the king of the devas, was once driven out of devaloka by an asura named Vritra. The asura was the recipient of a boon whereby he could not be killed by any weapon that was known till the date of his receiving the boon and additionally that no weapon made of wood or metal could harm him. Indra, who lost all hope of recovering his kingdom went to seek the aid of Vishnu. Vishnu revealed to Indra that only the weapon made from the bones of the sage Dadhichi would defeat Vritra. Indra and the other devas therefore approached the sage, whom Indra had once beheaded, and asked him for his aid in defeating Vritra. Dadhichi acceded to the devas' request but said that he wished that he had time to go on a pilgrimage to all the holy rivers before he gave up his life for them. Indra then brought together all the waters of the holy rivers to Naimisaranya, thereby allowing the sage to have his wish fulfilled without a further loss of time. Dadhichi is then said to have given up his life by the art of yoga after which the devas fashioned the Vajrayudha from his spine. This weapon was then used to defeat the asura, allowing Indra to reclaim his place as the king of devaloka.