CC Madhya 25.143-144
arthaḥ ayam — this is the meaning; brahma-sūtrāṇām — of the aphorisms of the Vedānta-sūtra; bhārata-artha-vinirṇayaḥ — the ascertainment of the Mahābhārata; gāyatrī-bhāṣya-rūpaḥ — the purport of Brahma-gāyatrī, the mother of the Vedic literatures; asau — that; veda-artha-paribṛṁhitaḥ — expanded by the meanings of all the Vedas; purāṇānām — of the Purāṇas; sāma-rūpaḥ — the best (like the Sāma among the Vedas); sākṣāt — directly; bhagavatā uditaḥ — spoken by Vyāsadeva, an incarnation of the Supreme Personality of Godhead; dvādaśa-skanda-yuktaḥ — having twelve cantos; ayam — this; śata-viccheda-saṁyutaḥ — having 335 chapters; granthaḥ — this great literature; aṣṭādaśa-sāhasraḥ — having 18,000 verses; śrīmad-bhāgavata-abhidhaḥ — named Śrīmad-Bhāgavatam.
“ ‘The meaning of the Vedānta-sūtra is present in Śrīmad-Bhāgavatam. The full purport of the Mahābhārata is also there. The commentary of the Brahma-gāyatrī is also there and fully expanded with all Vedic knowledge. Śrīmad-Bhāgavatam is the supreme Purāṇa, and it was compiled by the Supreme Personality of Godhead in His incarnation as Vyāsadeva. There are twelve cantos, 335 chapters and eighteen thousand verses.’
This is a quotation from the Garuḍa Purāṇa.