Romaharṣaṇa, a disciple of Vedavyāsa, divided the Purāṇas into four basic compilations. The sage Kaśyapa and I, along with Sāvarṇi and Akṛtavraṇa, a disciple of Rāma, learned these four divisions.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
कश्यपोऽहं च सावर्णी रामशिष्योऽकृतव्रणः । अधीमहि व्यासशिष्याच्चत्वारो मूलसंहिताः
kaśyapo'haṃ ca sāvarṇī rāmaśiṣyo'kṛtavraṇaḥ | adhīmahi vyāsaśiṣyāccatvāro mūlasaṃhitāḥ
SB 12.7.7