Srimad-Bhagavatam: Canto 6 - Chapter 1 - Verse 25
तद्विश्वरूपं भजताशु विप्रंतपस्विनं त्वाष्ट्रमथात्मवन्तम् ।सभाजितोऽर्थान् स विधास्यते वोयदि क्षमिष्यध्वमुतास्य कर्म ॥ २५ ॥
tad viśvarūpaṁ bhajatāśu vipraṁtapasvinaṁ tvāṣṭram athātmavantamsabhājito ’rthān sa vidhāsyate voyadi kṣamiṣyadhvam utāsya karma
O demigods, I instruct you to approach Viśvarūpa, the son of Tvaṣṭā, and accept him as your guru. He is a pure and very powerful brāhmaṇa undergoing austerity and penances. Pleased by your worship, he will fulfill your desires, provided that you tolerate his being inclined to side with the demons.
Lord Brahmā advised the demigods to accept the son of Tvaṣṭā as their spiritual master although he was always inclined toward the benefit of the asuras.