Bhagavad Gita: Chapter 15/Verse 20

इति गुह्यतमं शास्त्रमिदमुक्तं मयानघ ।

एतद्‌बुद्ध्वा बुद्धिमान्स्यात्कृतकृत्यश्च भारत ॥१५- २०॥

iti guhyatamaṃ śāstramidamuktaṃ mayānagha ।

etad‌buddhvā buddhimānsyātkṛtakṛtyaśca bhārata ॥15- 20॥

Thus, this is the most secret doctrine declared by me, O Blameless One. Having understood this, one ought to be wise and one who has done what needs to be done, Descendant of Bharata. 

iti (adverb) (indeclinable)  = thus 

guhyatamam (superlative, neuter, nominative, singular) = most secret 

śāstram (neuter, nominative, singular) = doctrine 

idam (pronoun, 3rd person, neuter, nominative, singular) = this 

uktam (past passive participle, neuter, nominative, singular) = declared 

mayā (pronoun, 1st person, instrumental, singular) = by me 

anagha (masculine, vocative, singular) = O Blameless One (epithet of Arjuna)  

etad‌ (pronoun, 3rd person, neuter, accusative, singular) = this 

buddhvā (gerund) (indeclinable) = having understood 

buddhimān (masculine, nominative, singular) = wise 

syāt (optative, 3rd person, singular) = one should be 

kṛtakṛtyas (masculine, nominative, singular) = one who has done what needs to be done

ca (conjunction) (indeclinable) = and 

bhārata = Descendant of Bharata (epithet of Arjuna)