Bhagavad Gita: Chapter 2/Verse 30

देही नित्यमवध्योऽयं देहे सर्वस्य भारत ।
तस्मात्सर्वाणि भूतानि न त्वं शोचितुमर्हसि ॥२- ३०॥

dehī nityamavadhyo'yaṃ dehe sarvasya bhārata ।
tasmātsarvāṇi bhūtāni na tvaṃ śocitumarhasi ॥2- 30॥

This embodied in the body of all is perpetually inviolable, O descendant-of-Bharata. Therefore, you should not grieve all beings.


Word-for-word translation

dehī (nominative, singular) = embodied 

nityam (adverb) (nominative, singular) = perpetually 

avadhyas (nominative, singular) = inviolable (cannot be killed)

ayam (demonstrative pronoun, nominative, singular) = this

dehe (locative, singular) = in the body

sarvasya (genitive, singular) = of all 

bhārata (vocative, singular) = O descendant-of-Bharata (epithet for Arjuna)

tasmāt (indeclinable) = therefore 

sarvāṇi (adjective) (accusative, singular) = all

bhūtāni (accusative, singular) = beings

na (adverb) (indeclinable) = not

tvam (pronoun, 2nd person, nominative, singular) = you

śocitum (infinitive) (indeclinable) = to grieve

arhasi (present tense, 2nd person, singular) = you should


Commentary 

"Avadhyas" is an interesting word meaning "one cannot be killed". Even in the English language the word "inviolable" meaning "one cannot be killed" is very rare in usage. 

"Deha" is the word for body in Sanskrit. The word "dehī" is the nominative case for the word "dehin" that means a "one possessed of a body", which most Sanskrit dictionaries list as "a being possessed of a body".  So one cannot simply translate "dehī" as "soul" because it is inherently connected to a word meaning "a body" by the base of the noun. Later in the verse is the word "dehe", which means "in the body." So the word "embodied" means "a being or soul possessed of a body".