B.G 2.26

अथ चैनं नित्यजातं नित्यं वा मन्यसे मृतम्। तथापि त्वं महाबाहो नैनं शोचितुमर्हसि ॥२-२६॥

atha cainaṃ nityajātaṃ nityaṃ vā manyase mṛtam। tathāpi tvaṃ mahābāho nainaṃ śocitum arhasi ॥2-26॥

[अथ (atha) - now; च (ca) - and; एनम् (enam) - this soul; नित्यजातम् (nityajātam) - eternally born; नित्यम् (nityam) - eternally; वा (vā) - or; मन्यसे (manyase) - you think; मृतम् (mṛtam) - dead; तथापि (tathāpi) - even then; त्वम् (tvam) - you; महाबाहो (mahābāho) - O mighty-armed one; न (na) - not; एनम् (enam) - this soul; शोचितुम् (śocitum) - to lament; अर्हसि (arhasi) - you ought; ॥२-२६॥ (॥2-26॥) - (verse 2-26);]

(Even if you believe the soul is perpetually born or perpetually dead, O mighty-armed one, you should not grieve for it.)

O mighty armed, even if you regard the being as inevitably born, and inevitably dying, it is not right for you to grieve.

Gīta Bhāshya 2.26

Birth and death are inevitable and hence there is no need to lament.

अस्त्वेवं आत्मनो नित्यत्वम् तथापि देहसंयोग वियोगात्मकजनिमृती स्त एव इत्यत आह 'अथ च' इति ॥२६॥

astvevaṃ ātmano nityatvam tathāpi dehasaṃyoga viyogātmakajanimṛtī sta eva ityata āha 'atha ca' iti ॥26॥

[अस्तु (astu) - let it be; एवम् (evam) - thus; आत्मनः (ātmanaḥ) - of the self; नित्यत्वम् (nityatvam) - eternity; तथापि (tathāpi) - nevertheless; देह (deha) - body; संयोग (saṃyoga) - union; वियोग (viyoga) - separation; आत्मक (ātmaka) - nature; जनि (jani) - birth; मृति (mṛti) - death; स्तः (staḥ) - are; एव (eva) - indeed; इत्यतः (ityataḥ) - therefore; आह (āha) - says; अथ (atha) - now; च (ca) - and; इति (iti) - thus;]

(Let it be accepted that the self is eternal; however, the nature of birth and death is indeed the union and separation of the body, therefore it is said 'now and thus'.)

Even though Jiva is everlasting, it still goes through the process of being born and dying in the form of uniting and separating from the body. Hence the "atha ca" verse.

Gīta Tātparya 2.26

The word 'nityam' in this verse means 'inevitable' based on context and dictionary.

तिष्ठतु तावत् अयं विस्तारः। यावन्मोक्षं जीवस्य जन्ममरणे स्वयमेव मन्यसे ननु नियमेन। तथापि तावन्मात्रेणापि ज्ञानेन शोचितुं नार्हसि।

tiṣṭhatu tāvat ayaṃ vistāraḥ। yāvanmokṣaṃ jīvasya janmamaraṇe svayameva manyase nanu niyamena। tathāpi tāvanmātreṇāpi jñānena śocituṃ nārhasi।

[तिष्ठतु (tiṣṭhatu) - let it remain; तावत् (tāvat) - for now; अयं (ayaṃ) - this; विस्तारः (vistāraḥ) - expansion; यावत् (yāvat) - as long as; मोक्षं (mokṣaṃ) - liberation; जीवस्य (jīvasya) - of the soul; जन्ममरणे (janmamaraṇe) - birth and death; स्वयमेव (svayameva) - by yourself; मन्यसे (manyase) - you consider; ननु (nanu) - indeed; नियमेन (niyamena) - by rule; तथापि (tathāpi) - still; तावन्मात्रेणापि (tāvanmātreṇāpi) - even with that much; ज्ञानेन (jñānena) - with knowledge; शोचितुं (śocituṃ) - to grieve; न (na) - not; अर्हसि (arhasi) - you should;]

(Let this expansion remain for now. As long as you consider liberation of the soul in birth and death by yourself indeed by rule. However, even with that much knowledge, you should not grieve.)

Despite the explanations provided so far, you must still wait to get liberated. In the meantime, birth and death are both subject to the law and unavoidable. With this minimal knowledge, it is clear that grieving is not worth it.

"नित्यं सनातनं प्रोक्तं नित्यं नियतमेव च।"

"nityaṁ sanātanaṁ proktaṁ nityaṁ niyatameva ca।"

[नित्यं (nityaṁ) - eternal; सनातनं (sanātanaṁ) - ancient; प्रोक्तं (proktaṁ) - spoken; नियतं (niyataṁ) - fixed; एव (eva) - indeed; च (ca) - and;]

(It is said to be eternal and ancient, and it is indeed fixed and eternal.)

'The word 'nitya'means that which is eternal. It also means that which cannot be avoided"

इति शब्दनिर्णये।

iti śabdanirṇaye।

[इति (iti) - thus; शब्द (śabda) - word; निर्णये (nirṇaye) - in the decision;]

- states "shabdanirnaya" dictionary.

अत्र तु नियतम्। 'जातस्य हि ध्रुवः' इति प्रकाशनात् ॥२६॥

atra tu niyatam। 'jātasya hi dhruvaḥ' iti prakāśanāt ॥26॥

[अत्र (atra) - here; तु (tu) - but; नियतम् (niyatam) - certain; जातस्य (jātasya) - of the born; हि (hi) - indeed; ध्रुवः (dhruvaḥ) - certain; इति (iti) - thus; प्रकाशनात् (prakāśanāt) - from the revelation;]

(Here, however, it is certain. 'For the born, indeed, is certain,' as revealed.)

The word 'nitya' should be interpreted as that which is inevitable. Because in the next verse "jātasya hi dhruvaḥ", a similar meaning is expressed using the word "dhruvaḥ".