महाभारतः mahābhārataḥ - book-1, chapter-54, verse-23

गुरोर्वचनमाज्ञाय स तु विप्रर्षभस्तदा ।
आचचक्षे ततः सर्वमितिहासं पुरातनम् ॥२३॥

23. gurorvacanamājñāya sa tu viprarṣabhastadā ,
ācacakṣe tataḥ sarvamitihāsaṁ purātanam.

23. guroḥ vacanam ājñāya saḥ tu viprarṣabhaḥ tadā
ācacakṣe tataḥ sarvam itihāsam purātanam

23. Having received the instruction from his guru, that best of brāhmaṇas then narrated in full that entire ancient history.

Words meanings summery:

• गुरोः (guroḥ) - from his guru (Vyāsa) (of the teacher, from the teacher)

• वचनम् (vacanam) - instruction (word, speech, instruction)

• आज्ञाय (ājñāya) - having understood/received (having known, having understood, having acknowledged)

• सः (saḥ) - he (Vaiśampāyana) (he)

• तु (tu) - indeed (but, indeed, yet)

• विप्रर्षभः (viprarṣabhaḥ) - that best of brāhmaṇas (best among brāhmaṇas)

• तदा (tadā) - then (then, at that time)

• आचचक्षे (ācacakṣe) - he narrated (he narrated, he told)

• ततः (tataḥ) - thereupon, then (then, thereupon, from that)

• सर्वम् (sarvam) - the entire (history) (all, everything)

• इतिहासम् (itihāsam) - this history/epic (history, legend, epic)

• पुरातनम् (purātanam) - ancient (ancient, old, primeval)

Words meanings and morphology

गुरोः (guroḥ) - from his guru (Vyāsa) (of the teacher, from the teacher)

(noun)

Ablative, masculine, singular of guru

guru - teacher, preceptor, respected person, heavy

Masculine noun ending in u.

Note: Refers to Vyāsa.

वचनम् (vacanam) - instruction (word, speech, instruction)

(noun)

Accusative, neuter, singular of vacana

vacana - speaking, saying, word, speech

action noun

From √vac (to speak) + ana suffix.

Root: vac (class 2)

आज्ञाय (ājñāya) - having understood/received (having known, having understood, having acknowledged)

(indeclinable)

indeclinable participle (absolutive/gerund)

From ā-√jñā (to know, to command) with lyap suffix.

Prefix: ā

Root: jñā (class 9)

सः (saḥ) - he (Vaiśampāyana) (he)

(pronoun)

Nominative, masculine, singular of tad

tad - that, he, she, it

Demonstrative pronoun.

Note: Subject of ācacakṣe.

तु (tu) - indeed (but, indeed, yet)

(indeclinable)

Particle.

विप्रर्षभः (viprarṣabhaḥ) - that best of brāhmaṇas (best among brāhmaṇas)

(noun)

Nominative, masculine, singular of viprarṣabha

viprarṣabha - chief of brahmins, best of sages

Tatpuruṣa compound (vipra + ṛṣabha).

Compound type : tatpuruṣa (vipra+ṛṣabha)

• vipra – inspired, wise, a brāhmaṇa
  noun (masculine)
• ṛṣabha – bull, best, chief
  noun (masculine)

Note: In apposition to saḥ.

तदा (tadā) - then (then, at that time)

(indeclinable)

Adverb of time.

आचचक्षे (ācacakṣe) - he narrated (he narrated, he told)

(verb)

3rd person , singular, middle, past perfect (liṭ) of ā-√cakṣ

perfect tense

Perfect 3rd person singular, middle voice. Reduplicated.

Prefix: ā

Root: cakṣ (class 2)

ततः (tataḥ) - thereupon, then (then, thereupon, from that)

(indeclinable)

Adverb of sequence.

सर्वम् (sarvam) - the entire (history) (all, everything)

(pronoun)

Accusative, masculine, singular of sarva

sarva - all, every, whole, entire

Indefinite pronoun/adjective.

इतिहासम् (itihāsam) - this history/epic (history, legend, epic)

(noun)

Accusative, masculine, singular of itihāsa

itihāsa - history, legend, traditional narrative, epic

Literally 'thus it was'. Compound of iti (thus) + ha (indeed) + āsa (it was).

Compound type : avyayībhāva (iti+ha+āsa)

• iti – thus, so
  indeclinable
• ha – indeed, surely
  indeclinable
• āsa – it was
  verb
  past tense
  Imperfect 3rd singular of √as
  Root: as (class 2)

Note: Object of ācacakṣe.

पुरातनम् (purātanam) - ancient (ancient, old, primeval)

(adjective)

Accusative, masculine, singular of purātana

purātana - old, ancient, former, primeval

Derived from purā (formerly) with tana suffix.