Kaṭha Upaniṣad 1.22

1.22

devair atrāpi vicikitsitaṃ kila tvaṃ ca mṛtyo yan na sujñeyam āttha /
vaktā cāsya tvādṛg anyo na labhyo nānyo varas tulya etasya kaścit //

[Naciketas :] 22. Even the gods had doubt, indeed, as to this, And thou, O Death, sayest that it is not easily to be understood. And another declarer of it the like of thee is not to be obtained. No other boon the equal of it is there at all.