1.2.10

jānāmy ahaṁ śevadhir ity anityaṁ na hy adhruvaiḥ prāpyate hi dhruvaṁ tat। tato mayā naciketaś cito'gniḥ anitya-dravyaiḥ prāptavān asmi nityam ॥10॥

I know this permnent treasure to be the lord conveyed by syllable 'A'; for the stable is not attained through the unstable. Therefore, having kindled the Naciketa fire with permanent materials, I have attained the eternal lord conveyed by syllable 'A'.

Bhāṣya 1.2.10

Key to understand above passage is to split 'anityam' as 'a-nityam', the permanent eternal lord conveyed by syllable 'A'. 'anityadravyaiḥ' is to be split as 'a-nitya-dravyaiḥ', the permanent raw materials such as topics covered in Nachiketa Agni (sacrifice, charity, and austerity) that enable attainment of the lord conveyed by syllable 'A'.

ākhyaṁ viṣṇv-ākhyaṁ nityaṁ śevadhir iti jānāmi। nityaṁ ākhya-viṣṇu-viṣayaiḥ dravyaiḥ manādi-bhiḥ। ākhya-nitya-viṣayaiḥ viṣṇv-ākhya-nitya-viṣayaiḥ dravyaiḥ। nityaṁ bhagavantaṁ prāptavān asmi। dhruvaḥ bhagavān। adhruvaiḥ tad-bhakti-varjitaiḥ na prāpyate ॥10॥

That which is conveyed by syllable 'A', conveys lord Vishnu; I know Him to be the eternal treasure. The permanent materials directed towards the lord Vishnu conveyed by syllable 'A' are mind and such others. Those materials concerning permanent topics conveyed by syllable 'A' are nothing but those permanent topics conveying lord Vishnu. The Lord is the stable one. He is not attained by the unstable who are devoid of His devotion.