To know about the Supreme Personality of Godhead and the characteristics of His pure devotee, one must inquire from authorities like Devarṣi Nārada. One cannot inquire about transcendental subject matters from a layman. As stated in Śrīmad-Bhāgavatam (3.25.25) , satāṁ prasaṅgān mama vīrya-saṁvido bhavanti hṛt-karṇa-rasāyanāḥ kathāḥ: only by association with devotees can one authoritatively understand the position of the Lord and His devotees. A devotee like Nārada Muni is addressed as suvrata. Su means “good,” and vrata means “vow.” Thus the word suvrata refers to a person who has nothing to do with the material world, which is always bad. One cannot understand anything spiritual from a materialistic scholar puffed up with academic knowledge. As stated in Bhagavad-gītā (18.55) , bhaktyā mām abhijānāti: one must try to understand Kṛṣṇa by devotional service and from a devotee. Therefore Yudhiṣṭhira Mahārāja was quite right in wanting to learn further about Prahlāda Mahārāja from Śrī Nārada Muni.