भवद्वधार्थं जनितस्त्वष्ट्रायं तपसा सुराः ।। वृत्रो नाम महातेजाः सर्वदैत्याधिपो महान् ।। १५ ।।
This Asura has been created by Tvaṣṭṛ by means of his penance in order to kill you. The name of that Asura is Vṛtra. He is of great brilliance and the leader of all Daityas.