The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 155

तस्यैषा दृष्टिर्यत्रैतदस्मिञ्छरीरे स५स्पर्शोनोष्णिमान विजानाति तस्यैषा श्रुतिर्यत्रैतत्कर्णावपिगृह्य निनदमिव नदथुरिवाग्नेरिव ज्वलत उपशृणोति तदेतद्दृष्टञ्च श्रुत चेत्युपासीत चक्षुष्य श्रुतो भवति य एव वेद य एवं वेद ॥ ८ ॥

In plain words

Of that inner reality, this is the visual sign: where one feels bodily warmth radiating within. And this is its auditory sign: where, closing both ears with one's fingers, one listens to the inner sound—resembling the roar of a rushing stream or the crackle of a blazing fire. One should meditate upon it as both seen and heard. Whoever knows this truly becomes dear to others and renowned.

Close to the Sanskrit

Of that, this is the sight: where one perceives warmth touching within this body. Of that, this is the hearing: where, having closed both ears, one hears as it were a sound, as it were a roaring, as it were of a blazing fire. One should meditate on that as seen and heard. He who thus knows, who thus knows, becomes dear and renowned.