Srimad-Bhagavatam: Canto 7 - Chapter 1 - Verse 2
अथाचार्यसुतस्तेषां बुद्धिमेकान्तसंस्थिताम् ।आलक्ष्य भीतस्त्वरितो राज्ञ आवेदयद्यथा ॥ २ ॥
athācārya-sutas teṣāṁbuddhim ekānta-saṁsthitāmālakṣya bhītas tvaritorājña āvedayad yathā
When Ṣaṇḍa and Amarka, the sons of Śukrācārya, observed that all the students, the sons of the demons, were becoming advanced in Kṛṣṇa consciousness because of the association of Prahlāda Mahārāja, they were afraid. They approached the King of the demons and described the situation as it was.
The words buddhim ekānta-saṁsthitām indicate that as an effect of Prahlāda Mahārāja’s preaching, the students who listened to him became fixed in the conclusion that Kṛṣṇa consciousness is the only object of human life. The fact is that anyone who associates with a pure devotee and follows his instructions becomes fixed in Kṛṣṇa consciousness and is not disturbed by materialistic consciousness. The teachers particularly observed this in their students, and therefore they were afraid because the whole community of students was gradually becoming Kṛṣṇa conscious.