SB 7.7.1

śrī-nārada uvāca
evaṁ daitya-sutaiḥ pṛṣṭo
 mahā-bhāgavato ’suraḥ
uvāca tān smayamānaḥ
 smaran mad-anubhāṣitam
Word for word: 
śrī-nāradaḥ uvāca — the great saint Nārada Muni said; evam — thus; daitya-sutaiḥ — by the sons of the demons; pṛṣṭaḥ — being questioned; mahā-bhāgavataḥ — the exalted devotee of the Lord; asuraḥ — born in a family of demons; uvāca — spoke; tān — unto them (the sons of the demons); smayamānaḥ — smiling; smaran — remembering; mat-anubhāṣitam — what was spoken by me.
Translation: 
Nārada Muni said: Although Prahlāda Mahārāja was born in a family of asuras, he was the greatest of all devotees. Having thus been questioned by his class friends, the sons of the asuras, he remembered the words spoken to him by me and replied to his friends as follows.
Purport: 

When he was in the womb of his mother, Prahlāda Mahārāja listened to the words of Nārada Muni. One cannot imagine how the baby in embryo could hear Nārada, but this is spiritual life; progress in spiritual life cannot be obstructed by any material condition. This is called ahaituky apratihatā. Reception of spiritual knowledge is never checked by any material condition. Thus Prahlāda Mahārāja, from his very childhood, spoke spiritual knowledge to his class friends, and certainly it was effective, although all of them were children.