tān āha karuṇo maitro
The words bālā adūṣita-dhiyaḥ indicate that the children, being of a tender age, were not as polluted by materialistic life as their fathers. Prahlāda Mahārāja, therefore, taking advantage of the innocence of his class friends, began teaching them about the importance of spiritual life and the insignificance of materialistic life. Although the teachers Ṣaṇḍa and Amarka were instructing all the boys in the materialistic life of religion, economic development and sense gratification, the boys were not much polluted. Therefore, with great attention they wanted to hear from Prahlāda Mahārāja about Kṛṣṇa consciousness. In our Kṛṣṇa consciousness movement, the gurukula plays an extremely important part in our activities because right from childhood the boys at the gurukula are instructed about Kṛṣṇa consciousness. Thus they become steady within the cores of their hearts, and there is very little possibility that they will be conquered by the modes of material nature when they are older.
Thus end the Bhaktivedanta purports of the Seventh Canto, Fifth Chapter, of the Śrīmad-Bhāgavatam, entitled “Prahlāda Mahārāja, the Saintly Son of Hiraṇyakaśipu.”