The Great Epic of the Bhārata dynasty 1.60.34

1.60.34

tvāṣṭrī tu saviturbhāryā vaḍavārūpadhāriṇī |
asūyata mahābhāgā sāntarikṣe'śvināvubhau || 34 ||

"And the son of Marichi is Kasyapa. And Kasyapa's offspring are the gods and the Asuras. And, therefore, is Kasyapa, the Father of the worlds. And Tvashtri, of the form of Vadava (a mare), became the wife of Savitri. And she gave birth, in the skies, to two greatly fortunate twins, the Aswins. And, O king, the sons of Aditi are twelve with Indra heading them all. And the youngest of them all was Vishnu upon whom the worlds depend.