SB 3.8.7
proktam kilaitad bhagavattamena
nivrtti-dharmabhirataya tena
sanat-kumaraya sa caha prstah
sankhyayanayanga dhrta-vrataya
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Sankarsana thus spoke the purport of Srimad-Bhagavatam to the great sage Sanat-kumara, who had already taken the vow of renunciation. Sanat-kumara also, in his turn, when inquired of by Sankhyayana Muni, explained Srimad-Bhagavatam as he had heard it from Sankarsana.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This is the way of the parampara system. Although Sanat-kumara, the well-known great saintly Kumara, was in the perfect stage of life, still he heard the message of Srimad-Bhagavatam from Lord Sankarsana. Similarly, when he was questioned by Sankhyayana Rsi, he spoke to him the same message he had heard from Lord Sankarsana. In other words, unless one hears from the proper authority one cannot become a preacher. In devotional service, therefore, two items out of the nine, namely hearing and chanting, are most important. Without hearing nicely, one cannot preach the message of Vedic knowledge.