Śatapatha Brāhmaṇa ("of a hundred paths") 11.5.7.2

11.5.7.2

ye ha vai ke ca śramāḥ ime dyāvāpṛthivī antareṇa svādhyāyo haiva teṣām paramatā kāṣṭhā ya evaṃ vidvāntsvādhyāyamadhīte tasmātsvādhyāyo'dhyetavyaḥ

And, truly, whatever may be the toils here between heaven and earth, the study (of the scriptures) is their last stage, their goal (limit) for him who, knowing this, studies his lesson: therefore one's (daily) lesson should be studied.