Srimad Bhagavatam Canto 03, Chapter 08, Text 03

SB 3.8.3

asinam urvyam bhagavantam adyam
 sankarsanam devam akuntha-sattvam
vivitsavas tattvam atah parasya
 kumara-mukhya munayo ’nvaprcchan
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Some time ago, being inquisitive to know, Sanat-kumara, the chief of the boy-saints, accompanied by other great sages, inquired exactly like you about the truths regarding Vasudeva, the Supreme, from Lord Sankarsana, who is seated at the bottom of the universe.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
This is in clarification of the statement that the Lord spoke directly on the Srimad-Bhagavatam. When and unto whom the Bhagavatam was spoken is explained herewith. Questions similar to those put forward by Vidura were asked by great sages like Sanat-kumara, and Lord Sankarsana, the plenary expansion of the Supreme Lord Vasudeva, answered them.
Srimad Bhagavatam Canto 03, Chapter 08, Text 02
Srimad Bhagavatam Canto 03, Chapter 08, Text 04