महाभारतः mahābhārataḥ - book-6, chapter-28, verse-6

बन्धुरात्मात्मनस्तस्य येनात्मैवात्मना जितः ।
अनात्मनस्तु शत्रुत्वे वर्तेतात्मैव शत्रुवत् ॥६॥

6. bandhurātmātmanastasya yenātmaivātmanā jitaḥ ,
anātmanastu śatrutve vartetātmaiva śatruvat.

6. bandhuḥ ātmā ātmanaḥ tasya yena ātmā eva ātmanā
jitaḥ anātmanaḥ tu śatrutve varteta ātmā eva śatruvat

6. yena ātmanā ātmā eva jitaḥ,
tasya ātmanaḥ ātmā bandhuḥ.
tu anātmanaḥ (puruṣasya) ātmā eva śatrutve śatruvat varteta.

6. For a person who has conquered their self (ātman) by their self, that self (ātman) is a friend. But for one who has not mastered their self, the self (ātman) indeed acts like an enemy.

Words meanings summery:

• बन्धुः (bandhuḥ) - a helpful ally or well-wisher (friend, relative, kinsman)

• आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

• आत्मनः (ātmanaḥ) - of the individual self (ātman) (of the self, of the soul)

• तस्य (tasya) - of that person (his, its, of that)

• येन (yena) - by that person (relative pronoun) (by whom, by which)

• आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

• एव (eva) - emphasizing the preceding word, 'the self indeed' (indeed, only, certainly)

• आत्मना (ātmanā) - by one's own efforts, by one's own self (ātman) (by the self, by the soul)

• जितः (jitaḥ) - brought under control, mastered (conquered, subdued, won)

• अनात्मनः (anātmanaḥ) - pertaining to a person who has not controlled their self (ātman) (of the uncontrolled self, of the not-self)

• तु (tu) - introducing a contrasting idea (but, on the other hand, however)

• शत्रुत्वे (śatrutve) - functioning as an adversary or foe (in the state of enmity, as an enemy)

• वर्तेत (varteta) - functions, behaves, or exists in a certain way (may act, should act, acts, behaves)

• आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

• एव (eva) - emphasizing the preceding word, 'the self indeed' (indeed, only, certainly)

• शत्रुवत् (śatruvat) - in the manner or guise of an enemy (like an enemy, as an enemy)

Words meanings and morphology

बन्धुः (bandhuḥ) - a helpful ally or well-wisher (friend, relative, kinsman)

(noun)

Nominative, masculine, singular of bandhu

bandhu - friend, kinsman, relative

आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

(noun)

Nominative, masculine, singular of ātman

ātman - self, soul, spirit, individual consciousness, supreme self

आत्मनः (ātmanaḥ) - of the individual self (ātman) (of the self, of the soul)

(noun)

Genitive, masculine, singular of ātman

ātman - self, soul, spirit, individual consciousness, supreme self

तस्य (tasya) - of that person (his, its, of that)

(pronoun)

Genitive, masculine, singular of tad

tad - that, it

येन (yena) - by that person (relative pronoun) (by whom, by which)

(pronoun)

Instrumental, masculine, singular of yad

yad - who, which, what, whereby

आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

(noun)

Nominative, masculine, singular of ātman

ātman - self, soul, spirit, individual consciousness, supreme self

एव (eva) - emphasizing the preceding word, 'the self indeed' (indeed, only, certainly)

(indeclinable)

आत्मना (ātmanā) - by one's own efforts, by one's own self (ātman) (by the self, by the soul)

(noun)

Instrumental, masculine, singular of ātman

ātman - self, soul, spirit, individual consciousness, supreme self

जितः (jitaḥ) - brought under control, mastered (conquered, subdued, won)

(adjective)

Nominative, masculine, singular of jita

jita - conquered, won, subdued, surpassed

Past Passive Participle

Derived from root 'ji' (to conquer)

Root: ji (class 1)

अनात्मनः (anātmanaḥ) - pertaining to a person who has not controlled their self (ātman) (of the uncontrolled self, of the not-self)

(noun)

Genitive, masculine, singular of anātman

anātman - not the self, non-self, uncontrolled self

Compound type : Nañ-tatpuruṣa (an+ātman)

• an – not, non-, un-
  indeclinable
  Negative prefix
• ātman – self, soul, spirit, individual consciousness, supreme self
  noun (masculine)

तु (tu) - introducing a contrasting idea (but, on the other hand, however)

(indeclinable)

शत्रुत्वे (śatrutve) - functioning as an adversary or foe (in the state of enmity, as an enemy)

(noun)

Locative, neuter, singular of śatrutva

śatrutva - enmity, hostility, the state of being an enemy

Abstract noun derived from 'śatru'

वर्तेत (varteta) - functions, behaves, or exists in a certain way (may act, should act, acts, behaves)

(verb)

3rd person , singular, active, optative (vidhiliṅ) of vṛt

Root: vṛt (class 1)

आत्मा (ātmā) - the individual self (ātman) or being (self, soul, spirit, individual consciousness)

(noun)

Nominative, masculine, singular of ātman

ātman - self, soul, spirit, individual consciousness, supreme self

एव (eva) - emphasizing the preceding word, 'the self indeed' (indeed, only, certainly)

(indeclinable)

शत्रुवत् (śatruvat) - in the manner or guise of an enemy (like an enemy, as an enemy)

(indeclinable)

Adverbial suffix -vat indicating similarity to 'śatru'