Kaṭha Upaniṣad 33

33

mṛtyoḥ pratijñā iyam -- pra te tubhyaṃ prabravīmi / yat tvayā prārthitaṃ tadu me mama vacaso nibodha budhyasvaikāgramanāḥ san svargyaṃ svargāya hitaṃ svargasādhanam agniṃ he naciketaḥ prajānan vijñātavān sann aham ity arthaḥ / prabravīmi tan nibodheti ca śiṣyabuddhisamādhānārthaṃ vacanam / adhunāgniṃ stauti -- anantaṃ lokāpti svargalokaphalaprāptisādhanam ity etat / atho 'pi pratiṣṭhām āśrayaṃ jagato virāḍrūpeṇa tam etam agniṃ mayocyamānaṃ viddhi vijānīhi tvaṃ nihitaṃ sthitaṃ guhāyāṃ viduṣāṃ buddhau niviṣṭam ity arthaḥ ///1,1.14 //

Shankara’s Commentary:
Com.—This is Death’s declaration. I will tell thee what has been solicited by thee; attend to what I say with concentrated mind. I know the fire, Oh Nachiketas, which helps one to heaven; ‘I will tell thee and attend’ are expressions used to concentrate the disciple's intellect; now he praises the fire, know this fire as leading to heaven and as the stay of the universe in its form of virat and as located in the intelligence of knowing men.