Vyasasmriti 3.10

3.10

itihāsapurāṇānāṃ vedopaniṣadāṃ dvijaḥ
śaktyā samyak paṭhennityamalpamapyāsamāpanāt

and of the Itihāsas, Purāṇas, and the Vedic Upaniṣads, the twice-born / should properly read daily according to his ability, even a small portion, until completion.