Bhagavatapurana 9.19.20

9.19.20

dṛṣṭaṃ śrutamasadbuddhvā nānudhyāyen na sandiśet /
saṃsṛtiṃ cātmanāśaṃ ca tatra vidvān sa ātmadṛk //

20. For, a man should see that both what is seen and what is heard are unreal, and should not think of, or associate with, them; and he becomes the seer of Atman who realises in them the source of samsara and the ruin of Atman.