From the very beginning of his childhood, Prahlāda Mahārāja was uninterested in childish playthings. Indeed, he gave them up altogether and remained silent and dull, being fully absorbed in Kṛṣṇa consciousness. Since his mind was always affected by Kṛṣṇa consciousness, he could not understand how the world goes on being fully absorbed in the activities of sense gratification.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
न्यस्तक्रीडनको बालो जडवत्तन्मनस्तया । कृष्णग्रहगृहीतात्मा न वेद जगदीदृशम्
nyastakrīḍanako bālo jaḍavattanmanastayā | kṛṣṇagrahagṛhītātmā na veda jagadīdṛśam
SB 7.4.37