Bhagavatapurana 3.26.14

3.26.14

mano buddhir ahaṅkāraś cittam ity antar-ātmakam /
caturdhā lakṣyate bhedo vṛttyā lakṣaṇa-rūpayā //

14. The internal organ has four aspects as *Manas*, *Buddhi*, *Ahankara* and *chitta*; and the fact of this four-fold distinction is observed through their characteristic functions.