महाभारतः mahābhārataḥ - book-12, chapter-323, verse-51

वैवस्वतेऽन्तरे विप्राः प्राप्ते त्रेतायुगे ततः ।
सुराणां कार्यसिद्ध्यर्थं सहाया वै भविष्यथ ॥५१॥

51. vaivasvate'ntare viprāḥ prāpte tretāyuge tataḥ ,
surāṇāṁ kāryasiddhyarthaṁ sahāyā vai bhaviṣyatha.

51. vaivasvate antare viprāḥ prāpte tretāyuge tataḥ
surāṇām kāryasiddhyartham sahāyāḥ vai bhaviṣyatha

51. viprāḥ vaivasvate antare tretāyuge prāpte tataḥ
surāṇām kāryasiddhyartham vai sahāyāḥ bhaviṣyatha

51. O brahmins, when the Tretā yuga arrives during the Vaivasvata manvantara, you will certainly become assistants for the fulfillment of the gods' tasks.

Words meanings summery:

• वैवस्वते (vaivasvate) - in the Vaivasvata manvantara (epoch of Manu Vaivasvata) (in relation to Vaivasvata; in the Vaivasvata (manvantara))

• अन्तरे (antare) - during the period (of the Vaivasvata manvantara) (in the middle; between; during; in the period)

• विप्राः (viprāḥ) - O brahmins (brahmins; inspired ones; sages)

• प्राप्ते (prāpte) - when the Tretā yuga has arrived (having reached; having obtained; when it has arrived)

• त्रेतायुगे (tretāyuge) - in the Tretā yuga (in the Tretā age/yuga)

• ततः (tataḥ) - then; thereafter (from that; then; thereafter)

• सुराणाम् (surāṇām) - of the gods

• कार्यसिद्ध्यर्थम् (kāryasiddhyartham) - for the fulfillment of the task (for the purpose of accomplishing a task; for the success of an undertaking)

• सहायाः (sahāyāḥ) - assistants (helpers; companions; assistants)

• वै (vai) - certainly (indeed; certainly; surely)

• भविष्यथ (bhaviṣyatha) - you (plural) will become (you (plural) will be)

Words meanings and morphology

वैवस्वते (vaivasvate) - in the Vaivasvata manvantara (epoch of Manu Vaivasvata) (in relation to Vaivasvata; in the Vaivasvata (manvantara))

(adjective)

Locative, masculine, singular of vaivasvata

vaivasvata - relating to Vaivasvata (Manu); descendent of Vivasvat (the Sun god)

derived from Vivasvat (the Sun god) + aṇ (taddhita suffix)

Note: Used here in reference to the Vaivasvata Manvantara, an epoch presided over by Manu Vaivasvata.

अन्तरे (antare) - during the period (of the Vaivasvata manvantara) (in the middle; between; during; in the period)

(noun)

Locative, neuter, singular of antara

antara - interior, middle, interval, period, within

Note: Used here to denote a specific period or epoch, specifically a manvantara.

विप्राः (viprāḥ) - O brahmins (brahmins; inspired ones; sages)

(noun)

Vocative, masculine, plural of vipra

vipra - brahmin, inspired, wise, sage

Root: vip (class 1)

प्राप्ते (prāpte) - when the Tretā yuga has arrived (having reached; having obtained; when it has arrived)

(adjective)

Locative, neuter, singular of prāpta

prāpta - obtained, reached, arrived, achieved

Past Passive Participle

from pra- (prefix) + āp (root) + ta (suffix)

Prefix: pra

Root: āp (class 5)

Note: Part of a locative absolute construction (tretāyuge prāpte).

त्रेतायुगे (tretāyuge) - in the Tretā yuga (in the Tretā age/yuga)

(noun)

Locative, neuter, singular of tretāyuga

tretāyuga - the second of the four ages (yugas) in Hindu cosmology

Compound type : tatpurusha (tretā+yuga)

• tretā – three; the second of the four yugas
  noun (feminine)
• yuga – age, epoch, period
  noun (masculine)

Note: Part of a locative absolute construction.

ततः (tataḥ) - then; thereafter (from that; then; thereafter)

(indeclinable)

adverbial suffix -tas

सुराणाम् (surāṇām) - of the gods

(noun)

Genitive, masculine, plural of sura

sura - god, deity

कार्यसिद्ध्यर्थम् (kāryasiddhyartham) - for the fulfillment of the task (for the purpose of accomplishing a task; for the success of an undertaking)

(indeclinable)

formed with artha (purpose)

Compound type : tatpurusha (kārya+siddhi+artha)

• kārya – work, task, duty, to be done
  noun (neuter)
  Gerundive
  from kṛ (root) + ya (suffix)
  Root: kṛ (class 8)
• siddhi – accomplishment, success, attainment, perfection
  noun (feminine)
  Root: sidh (class 4)
• artha – purpose, meaning, wealth, object
  noun (masculine)

Note: Adverbial use of an accusative of purpose or compound ending in -artha.

सहायाः (sahāyāḥ) - assistants (helpers; companions; assistants)

(noun)

Nominative, masculine, plural of sahāya

sahāya - helper, assistant, companion, associate

Prefix: saha

Root: i (class 2)

Note: Predicate nominative for bhaviṣyatha.

वै (vai) - certainly (indeed; certainly; surely)

(indeclinable)

Note: An emphatic particle.

भविष्यथ (bhaviṣyatha) - you (plural) will become (you (plural) will be)

(verb)

2nd person , plural, active, future (lṛṭ) of bhū

Future Tense, 2nd Person Plural, Parasmaipada

from bhū (root) + sya (future stem suffix) + tha (2nd pl ending)

Root: bhū (class 1)