Srimad-Bhagavatam: Canto 6 - Chapter 1 - Verse 39
Sanskrit:
एतत्ते सर्वमाख्यातं यन्मां त्वं परिपृच्छसि ।वृत्रस्यासुरजातेश्च कारणं भगवन्मते: ॥ ३९ ॥
ITRANS:
etat te sarvam ākhyātaṁyan māṁ tvaṁ paripṛcchasivṛtrasyāsura-jāteś cakāraṇaṁ bhagavan-mateḥ
Translation:
My dear King Parīkṣit, you inquired from me how Vṛtrāsura, a great devotee, took birth in a demoniac family. Thus I have tried to explain to you everything about this.