The Religion and Philosophy of the Veda and Upanishads v1.c20.s2.4

v1.c20.s2.4

Tvaṣṭṛ stands in special relation to the human race in that his daughter Saraṇyū, wife of Vivasvant, produced the twins, Yama and Yamī, whence came the human race. He is also father of Bṛhaspati, of Agni, and even of Indra, who, however, seems to have slain him for withholding from him the Soma. Indra also was hostile to Viçvarūpa, the three-headed son of Tvaṣṭṛ, from whom he sought to win the cows: he slew Viçvarūpa, and, when Tvaṣṭṛ in anger refused to allow him to take part in his Soma sacrifice, Indra came and drank the Soma by force.² As Tvaṣṭṛ is himself called more often than any other god Viçvarūpa, it is difficult not to suspect that the connexion of Tvaṣṭṛ with Viçvarūpa of the three heads is due to the similarity of name, and it is perhaps hence that there arises the hostility between Tvaṣṭṛ and Indra: the old character of the Viçvarūpa myth is vouched for by its Indo-European parallels. As son in law of Tvaṣṭṛ Vāyu once is mentioned.