Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 36
Sanskrit:
तत्र दानवदैत्यानां सङ्गात्ते भाव आसुर: ।दृष्ट्वा मदनुभावं वै सद्य: कुण्ठो विनङ्क्ष्यति ॥ ३६ ॥
ITRANS:
tatra dānava-daityānāṁsaṅgāt te bhāva āsuraḥdṛṣṭvā mad-anubhāvaṁ vaisadyaḥ kuṇṭho vinaṅkṣyati
Translation:
Because there you will see My supreme prowess, your materialistic ideas and anxieties that have arisen from your association with the demons and Dānavas will immediately be vanquished.
Purport:
The Lord assured Bali Mahārāja of all protection, and finally the Lord assured him of protection from the effects of bad association with the demons. Bali Mahārāja certainly became an exalted devotee, but he was somewhat anxious because his association was not purely devotional. The Supreme Personality of Godhead therefore assured him that his demoniac mentality would be annihilated. In other words, by the association of devotees, the demoniac mentality is vanquished. When a demon associates with devotees engaged in glorifying the Supreme Personality of Godhead, he gradually becomes a pure devotee.