योगवासिष्ठः yogavāsiṣṭhaḥ - book-6, chapter-81, verse-91

अग्निर्नष्टतया शैत्यादसावेव प्रयाति यत् ।
विनाशपरिणामेन तदग्निः सोमकारणम् ॥ ९१ ॥

agnirnaṣṭatayā śaityādasāveva prayāti yat ,
vināśapariṇāmena tadagniḥ somakāraṇam 91

91. agniḥ naṣṭatayā śaityāt asau eva prayāti yat
| vināśa-pariṇāmena tat agniḥ soma-kāraṇam ||

91. yat agniḥ śaityāt naṣṭatayā asau eva prayāti
tat agniḥ vināśa-pariṇāmena soma-kāraṇam

91. When fire (agni), through its destruction by cold, itself undergoes a transformative decay and attains (a state of non-existence), that very fire (agni) is the cause of Soma (soma).

Words meanings summery:

• अग्निः (agniḥ) - fire (agni)

• नष्टतया (naṣṭatayā) - by being destroyed, in the state of destruction

• शैत्यात् (śaityāt) - from cold, due to cold

• असौ (asau) - that one, it (demonstrative pronoun, masculine/feminine nominative singular)

• एव (eva) - indeed, certainly, only, just

• प्रयाति (prayāti) - goes towards, attains, reaches

• यत् (yat) - which, what, that (neuter nominative/accusative singular relative pronoun); inasmuch as, because (indeclinable)

• विनाश-परिणामेन (vināśa-pariṇāmena) - by transformation of destruction, by a destructive transformation, by a transformation into decay

• तत् (tat) - that (neuter nominative/accusative singular)

• अग्निः (agniḥ) - fire (agni)

• सोम-कारणम् (soma-kāraṇam) - cause of Soma (soma)

Words meanings and morphology

अग्निः (agniḥ) - fire (agni)

(noun)

Nominative, masculine, singular of agni

agni - fire, the deity Agni

नष्टतया (naṣṭatayā) - by being destroyed, in the state of destruction

(noun)

Instrumental, feminine, singular of naṣṭatā

naṣṭatā - state of destruction, ruin

Derived from naṣṭa (destroyed, past passive participle) + tā (suffix for state/quality).

शैत्यात् (śaityāt) - from cold, due to cold

(noun)

Ablative, neuter, singular of śaitya

śaitya - coldness, chill

असौ (asau) - that one, it (demonstrative pronoun, masculine/feminine nominative singular)

(pronoun)

Nominative, masculine, singular of adas

adas - that, that one, yonder

एव (eva) - indeed, certainly, only, just

(indeclinable)

प्रयाति (prayāti) - goes towards, attains, reaches

(verb)

3rd person , singular, active, present (laṭ) of yā

Prefix: pra

Root: yā (class 2)

यत् (yat) - which, what, that (neuter nominative/accusative singular relative pronoun); inasmuch as, because (indeclinable)

(pronoun)

Nominative, neuter, singular of yad

yad - which, what, that (relative pronoun); because, inasmuch as (indeclinable)

विनाश-परिणामेन (vināśa-pariṇāmena) - by transformation of destruction, by a destructive transformation, by a transformation into decay

(noun)

Instrumental, masculine, singular of vināśa-pariṇāma

vināśa-pariṇāma - transformation involving destruction or decay

Compound type : ṣaṣṭhī-tatpuruṣa (vināśa+pariṇāma)

• vināśa – destruction, decay, annihilation
  noun (masculine)
  Prefix: vi
  Root: naś (class 4)
• pariṇāma – transformation, change, evolution, maturation
  noun (masculine)
  Prefix: pari
  Root: nam (class 1)

तत् (tat) - that (neuter nominative/accusative singular)

(pronoun)

Nominative, neuter, singular of tad

tad - that, this

अग्निः (agniḥ) - fire (agni)

(noun)

Nominative, masculine, singular of agni

agni - fire, the deity Agni

सोम-कारणम् (soma-kāraṇam) - cause of Soma (soma)

(noun)

Nominative, neuter, singular of soma-kāraṇa

soma-kāraṇa - cause of Soma

Compound type : ṣaṣṭhī-tatpuruṣa (soma+kāraṇa)

• soma – moon, Soma plant/drink, water, nectar
  noun (masculine)
• kāraṇa – cause, reason, instrument
  noun (neuter)
  Root: kṛ (class 8)