The earliest mention of the Vajra is in the Rigveda, a part of four Vedas. It is described as the weapon of Indra, the god of heaven and the chief deity of the Rigvedic pantheon. Indra is described as using the Vajra to kill sinners and ignorant persons. The Rigveda states that the weapon was made for Indra by Tvastar, the maker of divine instruments. The associated story describes Indra using the Vajra, which he held in his hand, to slay the Asura Vritra, who took the form of a serpent.
On account of his skill in wielding the Vajra, some epithets used for Indra in the Rigveda were Vajrabhrit (bearing the bolt), Vajrivat or Vajrin (armed with the bolt), Vajradaksina (holding the bolt in his right hand), and Vajrabahu or Vajrahasta (holding the Vajra in his hand). The association of the Vajra with Indra was continued with some modifications in the later Puranic literature, and in Buddhist works. Buddhaghosa, a major figure of Theravada Buddhism in the 5th century, identified the Bodhisattva Vajrapani with Indra.