Bhagavad Gita: Chapter 6/Verse 6

बन्धुरात्मात्मनस्तस्य येनात्मैवात्मना जितः ।

अनात्मनस्तु शत्रुत्वे वर्तेतात्मैव शत्रुवत् ॥६- ६॥

bandhurātmātmanastasya yenātmaivātmanā jitaḥ ।
anātmanastu śatrutve vartetātmaiva śatruvat ॥6- 6॥

Of that one with whom is a friend, indeed, is a self of the self; however, indeed, the self subdued by the self of the non-self will exist in enmity like an enemy.

bandhus (masculine, nominative, singular) = friend

ātmā (masculine, nominative, singular) = self 

ātmanas (masculine, genitive, singular) = of the self 

tasya (pronoun, 3rd person, masculine, genitive, singular) = of that one 

yena (pronoun, 3rd person, masculine, instrumental, singular) = with whom

ātmā (masculine, nominative, singular) = self 

eva (adverb) (indeclinable) = indeed 

ātmanā (masculine, instrumental, singular) = by the self 

jitas (past passive participle, masculine, nominative, singular) = subdued 

anātmanas (masculine, genitive, singular) = of the non-self 

tu (conjunction) (indeclinable) = but 

śatrutve (masculine, locative, singular) = in enmity  

varteta (optative, 3rd person, singular) = will exist 

ātmā (masculine, nominative, singular) = the self 

eva (adverb) (indeclinable) = indeed 

śatruvat (neuter, nominative, singular) = like an enemy


Commentary

This verse is a tongue twister. Previous translations deal with this complicated tongue twister by inserting words that are not in the original script or severely bend the meaning of a word in the text. For example, other translations insert the phrase "who has not conquered". This word is nowhere in the text. I believe the past translations use "anātmanas" to mean "who has not conquered", but this is a serious bending of the meaning of the word. Plus, the syntax of the other translations is chaotic and does not make sense. My translation is very literal and it may be hard to understand. The basic gist of the verse is that the non-self is an enemy of the self and the self is a friend of the self. In other words, one should always be true to oneself.