SB 1.7 - Vyāsa's revision of Śrīmad Bhāgavatam
Śrīmad Bhāgavatam is the natural commentary on the Brahma-sūtras compiled by the same author. After compiling the Vedas and summarizing their conclusions in the Vedānta-sūtra, Vyāsa experienced his revelation about the Absolute Truth and then wrote and revised the Bhāgavatam. Although the Bhāgavatam is meant for the paramahaṁsas, or those totally engaged in self realization, it works into the depths of the hearts of those who may be worldly men, who can find remedial measures for their material diseases. Vyāsa first gave a synopsis of Bhāgavatam and then gave a detailed description under instruction of Nārada. Nārada gave instructions after the disappearance of Kṛṣṇa and before Parīkṣit punished Kali because even at that time there was a tendency towards irreligion among everyone. Vyāsa was dissatisfied in his heart because of this. It is understood that before the beginning of Kali-yuga he would not have been dissatisfied in heart. Now at this time he revised the Bhāgavatam which was previously written.
When he compiled the Purāṇas, Vyāsa compiled the Bhāgavatam in an abbreviated form, and later having been instructed by Nārada and experiencing his own realizations, he revised the Bhāgavatam. The revised Bhāgavatam is the one that is referred when it says it arose after the departure of Kṛṣṇa. Again it is the present Bhāgavatam that is referred to when it is said that it is one among the 18 Purāṇas. Then Vyāsa taught it to his own son, Śuka, who was already engaged in self realization (nivṛtti mārga). The path of pravṛtti mārga was condemned by Nārada, and Bhāgavatam is the science for those following the path of nivṛtti mārga. Bhāgavatam was compiled not less than five thousand years ago.