SB 1.7.1

śaunaka uvāca
nirgate nārade sūta
 bhagavān bādarāyaṇaḥ
śrutavāṁs tad-abhipretaṁ
 tataḥ kim akarod vibhuḥ
Synonyms: 
śaunakaḥ — Śrī Śaunaka; uvāca — said; nirgate — having gone; nārade — Nārada Muni; sūta — O Sūta; bhagavān — the transcendentally powerful; bādarāyaṇaḥ — Vedavyāsa; śrutavān — who heard; tat — his; abhipretam — desire of the mind; tataḥ — thereafter; kim — what; akarot — did he do; vibhuḥ — the great.
Translation: 
Ṛṣi Śaunaka asked: O Sūta, the great and transcendentally powerful Vyāsadeva heard everything from Śrī Nārada Muni. So after Nārada’s departure, what did Vyāsadeva do?
Purport: 

In this chapter the clue for describing Śrīmad-Bhāgavatam is picked up as Mahārāja Parīkṣit is miraculously saved in the womb of his mother. This was caused by Drauṇi (Aśvatthāmā), Ācārya Droṇa’s son, who killed the five sons of Draupadī while they were asleep, for which he was punished by Arjuna. Before commencing the great epic Śrīmad-Bhāgavatam, Śrī Vyāsadeva realized the whole truth by trance in devotion.