1.3.01 and 02
ऋतं पिबन्तौ सुकृतस्य लोके गुहां प्रविष्टौ परमे परार्द्धे। छायातपौ ब्रह्मविदो वदन्ति पञ्चाग्नयो ये च त्रिनाचिकेताः ॥१॥
यः सेतुरीजानानां अक्षरं ब्रह्म तत्परम्। अभयं तितीर्षतां पारं नाचिकेतं शकेमसि ॥२॥
ṛtaṁ pibantau sukṛtasya loke guhāṁ praviṣṭau parame parārdhe। chāyātapau brahmavido vadanti pañcāgnayo ye ca trināciketāḥ ॥1॥ yaḥ setur ījānānāṁ akṣaraṁ brahma tatparam। abhayaṁ titīrṣatāṁ pāraṁ nāciketaṁ śakemasi ॥2॥
[ऋतम् (ṛtam) - truth / natural ordained routine; पिबन्तौ (pibantau) - the two drinkers; सुकृतस्य (sukṛtasya) - of the virtuous; लोके (loke) - in the world; गुहाम् (guhām) - the cave (of the heart); प्रविष्टौ (praviṣṭau) - who have entered; परमे (parame) - in the supreme; परार्धे (parārdhe) - highest quarter; छायातपौ (chāyātapau) - shade and heat; ब्रह्मविदः (brahmavidaḥ) - knowers of Brahman; वदन्ति (vadanti) - say; पञ्चाग्नयः (pañcāgnayaḥ) - performers of five fires; ये (ye) - who; च (ca) - and; त्रिनाचिकेताः (trināciketāḥ) - those who have thrice performed the Naciketas rite; यः (yaḥ) - who; सेतु: (setuḥ) - the bridge; ईजानानाम् (ījānānām) - of the sacrificers; अक्षरम् (akṣaram) - imperishable; ब्रह्म (brahma) - Brahman; तत् (tat) - that; परम् (param) - supreme; अभयम् (abhayam) - fearlessness; तितीर्षताम् (titīrṣatām) - of those who wish to cross; पारम् (pāram) - to the far shore; नाचिकेतम् (nāciketam) - the Naciketas (means); शकेमसि (śakemasi) - we are able;]
The knowers of Brahman, the five-fire sacrificers, and those who have thrice performed the Naciketas rite, having entered the cave in the supreme highest quarter say - "The two, shade and heat", are drunk by the performers of ṛtam, i.e. those engaged in naturally ordained routine, in this benevolent world. The Naciketas are able to reach that which is the bridge for the sacrificers, the fearlessness and the far shore - for those who seek to cross, the imperishable supreme Brahman.
Bhāṣya 1.3.01 and 02
A testimonial is provided where the critical word 'chāyātapau' is explained as the two forms of the lord - for the wise he is like shade ('chāyeva'), for the sinners he is heat ('ātapaḥ').
आत्मान्तरात्मेति विभुः एक एव द्विधा स्थितः। स विष्णुः परमे वायौ परेभ्योऽप्यृद्धरूपके॥ शुभान् पिबति भोगान् सः छायेव विदुषां प्रभुः। आतपः पापिनां नित्यं मर्यादा विष्णुयाजिनाम्॥ संसारस्य च पारस्थः स विष्णुर्द्विस्वरूपकः॥
ātmāntarātmeti vibhuḥ eka eva dvidhā sthitaḥ। sa viṣṇuḥ parame vāyau parebhyo'pyṛddharūpake॥ śubhān pibati bhogān saḥ chāyeva viduṣāṁ prabhuḥ। ātapaḥ pāpināṁ nityaṁ maryādā viṣṇuyājinām॥ saṁsārasya ca pārasthaḥ sa viṣṇurdvisvarūpakaḥ॥
[आत्मा-अन्तरात्मा-इति (ātmā-antarātmā-iti) - as the self and the inner self; विभुः (vibhuḥ) - the all-pervading; एकः (ekaḥ) - one; एव (eva) - indeed; द्विधा (dvidhā) - in two forms; स्थितः (sthitaḥ) - established; सः (saḥ) - he; विष्णुः (viṣṇuḥ) - Viṣṇu; परमे (parame) - in the supreme; वायौ (vāyau) - in air; परेभ्यः (parebhyaḥ) - beyond others; अपि (api) - even; ऋद्धरूपके (ṛddharūpake) - in a form of excellence; शुभान् (śubhān) - auspicious; पिबति (pibati) - enjoys; भोगान् (bhogān) - pleasures; सः (saḥ) - he; छायेव (chāyeva) - like shade; विदुषाम् (viduṣām) - of the wise; प्रभुः (prabhuḥ) - the lord; आतपः (ātapaḥ) - heat; पापिनाम् (pāpinām) - for the sinners; नित्यं (nityaṁ) - always; मर्यादा (maryādā) - the boundary; विष्णुयाजिनाम् (viṣṇuyājinām) - for the worshippers of Viṣṇu; संसारस्य (saṁsārasya) - of the world; च (ca) - and; पारस्थः (pārasthaḥ) - beyond the shore; सः (saḥ) - he; विष्णुः (viṣṇuḥ) - Viṣṇu; द्विस्वरूपकः (dvisvarūpakaḥ) - of dual form;]
"The all-pervading one is called the self and the inner self, and is established in two forms. He, Viṣṇu, resides in the supreme air, in a form beyond others and full of excellence. He enjoys auspicious pleasures; for the wise he is like shade ('chāyeva'), for the sinners he is heat ('ātapaḥ'), always the boundary for the worshippers of Viṣṇu. He, Viṣṇu of dual form, stands beyond the shore of worldly existence."
