Kaṭha Upaniṣad 2.9

2.9

naiṣā tarkeṇa matir āpaneyā proktānyenaiva sujñānāya preṣṭha /
yāṃ tvam āpaḥ satyadhṛtir batāsi tvādṛṅ no bhūyān naciketaḥ preṣṭā //

9. Not by reasoning (_tarka_) is this thought (_mati_) to be attained.
Proclaimed by another, indeed, it is for easy understanding,
dearest friend (_preṣṭha_)!—
This which thou hast attained! Ah, thou art of true stead-
fastness!
May there be for us a questioner (_praṣṭā_) the like of thee,
O Naciketas!