देवैरत्रापि विचिकित्सितं किलत्वं च मृत्यो यन्न सुज्ञेयमात्थ ।
वक्ता चास्य त्वादृगन्यो न लभ्यो नान्यो वरस्तुल्य एतस्य कश्चित् ॥ २२ ॥

devairatrāpi vicikitsitaṃ kilatvaṃ ca mṛtyo yanna sujñeyamāttha |
vaktā cāsya tvādṛganyo na labhyo nānyo varastulya etasya kaścit || 22 ||

22. Thou sayest, Oh Death, that even the gods had doubts here and that this is not easy to know. None other like thee, who could tell of this, can be found; no other boon can at all equal this.

Shankara’s Commentary:

Thus addressed, Nachiketas said, ‘I have heard from yourself that even the gods had doubt on this point and you say, Oh Death, that the true nature of the atman is not easy to know. As this cannot be known even by the learned, another, learned like you 2 to explain this, cannot be found, though sought.’ This boon also is a means to the attainment of emancipation and there is no other boon which can at all weigh with this. The meaning is that other boons bear only transitory fruits.