महाभारतः mahābhārataḥ - book-1, chapter-49, verse-19

भव स्वस्थमना नाग न हि ते विद्यते भयम् ।
प्रयतिष्ये तथा सौम्य यथा श्रेयो भविष्यति ।
न मे वागनृतं प्राह स्वैरेष्वपि कुतोऽन्यथा ॥१९॥

19. bhava svasthamanā nāga na hi te vidyate bhayam ,
prayatiṣye tathā saumya yathā śreyo bhaviṣyati ,
na me vāganṛtaṁ prāha svaireṣvapi kuto'nyathā.

19. bhava svasthamanāḥ nāga na hi te
vidyate bhayam prayatiṣye tathā saumya
yathā śreyaḥ bhaviṣyati na me vāk
anṛtam prāha svair_eṣu api kutaḥ anyathā

19. O Nāga, be at ease in your mind, for indeed there is no fear for you. O gentle one, I will strive in such a way that good fortune will come to pass. My word never speaks a falsehood, even in my free moments; how could it be otherwise (now)?

Words meanings summery:

• भव (bhava) - be (be, become)

• स्वस्थमनाः (svasthamanāḥ) - at ease in mind (composed in mind, tranquil-minded, at ease)

• नाग (nāga) - O Nāga (O serpent (king))

• न (na) - not

• हि (hi) - indeed (indeed, surely, because)

• ते (te) - for you (to you, your)

• विद्यते (vidyate) - exists (exists, is found)

• भयम् (bhayam) - fear (fear, dread)

• प्रयतिष्ये (prayatiṣye) - I will strive (I will endeavor, I will strive)

• तथा (tathā) - in such a way (so, in that way)

• सौम्य (saumya) - O gentle one (O gentle one, O benevolent one)

• यथा (yathā) - so that (as, so that)

• श्रेयः (śreyaḥ) - good fortune, success (welfare, good fortune, prosperity)

• भविष्यति (bhaviṣyati) - will come to pass (will be, will happen)

• न (na) - not

• मे (me) - my (my, to me)

• वाक् (vāk) - my speech/word (word, speech)

• अनृतम् (anṛtam) - a falsehood (untruth, falsehood)

• प्राह (prāha) - speaks (speaks, has said)

• स्वैर्_एषु (svair_eṣu) - even in my free moments / casual talk (in free/unrestrained circumstances, in one's own affairs/leisure)

• अपि (api) - even (also, even)

• कुतः (kutaḥ) - how (could it be) (whence, how, why)

• अन्यथा (anyathā) - otherwise (otherwise, differently)

Words meanings and morphology

भव (bhava) - be (be, become)

(verb)

2nd person , singular, active, imperative (lot) of bhū

Root: bhū (class 1)

स्वस्थमनाः (svasthamanāḥ) - at ease in mind (composed in mind, tranquil-minded, at ease)

(adjective)

Nominative, masculine, singular of svasthamanas

svasthamanas - of sound mind, composed, tranquil-minded, at ease

Compound type : bahuvrīhi (svastha+manas)

• svastha – at ease, healthy, self-reliant
  adjective (masculine)
• manas – mind, intellect, thought, heart
  noun (neuter)

नाग (nāga) - O Nāga (O serpent (king))

(noun)

Vocative, masculine, singular of nāga

nāga - serpent, snake, elephant, Nāga (a mythical serpent-being)

न (na) - not

(indeclinable)

हि (hi) - indeed (indeed, surely, because)

(indeclinable)

ते (te) - for you (to you, your)

(pronoun)

Dative, singular of yuṣmad

yuṣmad - you

Note: Can also be genitive

विद्यते (vidyate) - exists (exists, is found)

(verb)

3rd person , singular, middle, present indicative (lat) of vid

Root: vid (class 4)

भयम् (bhayam) - fear (fear, dread)

(noun)

Nominative, neuter, singular of bhaya

bhaya - fear, dread, apprehension

action noun

From √bhī

Root: bhī (class 3)

प्रयतिष्ये (prayatiṣye) - I will strive (I will endeavor, I will strive)

(verb)

1st person , singular, middle, future (lṛṭ) of yat

Prefix: pra

Root: yat (class 1)

तथा (tathā) - in such a way (so, in that way)

(indeclinable)

सौम्य (saumya) - O gentle one (O gentle one, O benevolent one)

(adjective)

Vocative, masculine, singular of saumya

saumya - gentle, benevolent, auspicious, lunar, belonging to Soma

यथा (yathā) - so that (as, so that)

(indeclinable)

श्रेयः (śreyaḥ) - good fortune, success (welfare, good fortune, prosperity)

(noun)

Nominative, neuter, singular of śreyas

śreyas - welfare, good, excellence, bliss, better

भविष्यति (bhaviṣyati) - will come to pass (will be, will happen)

(verb)

3rd person , singular, active, future (lṛṭ) of bhū

Root: bhū (class 1)

न (na) - not

(indeclinable)

मे (me) - my (my, to me)

(pronoun)

Genitive, singular of asmad

asmad - I, we

Note: Can also be dative

वाक् (vāk) - my speech/word (word, speech)

(noun)

Nominative, feminine, singular of vāc

vāc - speech, word, voice, language

अनृतम् (anṛtam) - a falsehood (untruth, falsehood)

(noun)

Accusative, neuter, singular of anṛta

anṛta - untruth, falsehood; false, untrue

प्राह (prāha) - speaks (speaks, has said)

(verb)

3rd person , singular, active, perfect (lit) of ah

Prefix: pra

Root: ah (class 2)

Note: Used here in a present/gnomic sense

स्वैर्_एषु (svair_eṣu) - even in my free moments / casual talk (in free/unrestrained circumstances, in one's own affairs/leisure)

(adjective)

Locative, masculine, plural of svaira

svaira - free, independent, self-willed, sportive, unrestrained, own

अपि (api) - even (also, even)

(indeclinable)

कुतः (kutaḥ) - how (could it be) (whence, how, why)

(indeclinable)

अन्यथा (anyathā) - otherwise (otherwise, differently)

(indeclinable)