महाभारतः mahābhārataḥ - book-3, chapter-80, verse-63

अगस्त्यसर आसाद्य पितृदेवार्चने रतः ।
त्रिरात्रोपोषितो राजन्नग्निष्टोमफलं लभेत् ॥६३॥

63. agastyasara āsādya pitṛdevārcane rataḥ ,
trirātropoṣito rājannagniṣṭomaphalaṁ labhet.

63. agastyasaraḥ āsādya pitṛdevārcane rataḥ
trirātropoṣitaḥ rājan agniṣṭomaphalam labhet

63. O King, one who, having reached Agastya's lake, is devoted to the worship of ancestors and deities, and has fasted for three nights, will obtain the merit of the Agniṣṭoma sacrifice.

Words meanings summery:

• अगस्त्यसरः (agastyasaraḥ) - the lake associated with the sage Agastya (Agastya's lake)

• आसाद्य (āsādya) - having reached, having attained, having approached

• पितृदेवार्चने (pitṛdevārcane) - in the worship of ancestors and gods

• रतः (rataḥ) - devoted to, engaged in (delighted in, engaged in, attached to)

• त्रिरात्रोपोषितः (trirātropoṣitaḥ) - one who has fasted for three nights

• राजन् (rājan) - O King

• अग्निष्टोमफलम् (agniṣṭomaphalam) - the merit obtained from performing the Agniṣṭoma sacrifice (the fruit or result of the Agniṣṭoma sacrifice)

• लभेत् (labhet) - should obtain, may obtain, would obtain

Words meanings and morphology

अगस्त्यसरः (agastyasaraḥ) - the lake associated with the sage Agastya (Agastya's lake)

(proper noun)

Accusative, neuter, singular of agastyasaras

agastyasaras - Agastya's lake

Compound type : ṣaṣṭhī-tatpuruṣa (agastya+saras)

• agastya – name of a celebrated Vedic sage
  proper noun (masculine)
• saras – lake, pond, pool
  noun (neuter)

आसाद्य (āsādya) - having reached, having attained, having approached

(indeclinable)

absolutive (gerund)

Derived from the root sad (to sit) with upasarga ā (to, towards) and the suffix -ya for absolutive.

Prefix: ā

Root: sad (class 1)

Note: Absolutive (gerund) form.

पितृदेवार्चने (pitṛdevārcane) - in the worship of ancestors and gods

(noun)

Locative, neuter, singular of pitṛdevārcana

pitṛdevārcana - worship of ancestors and gods

Compound type : dvandva/tatpuruṣa (pitṛ+deva+arcana)

• pitṛ – father, ancestor
  noun (masculine)
• deva – god, deity
  noun (masculine)
• arcana – worship, adoration, honoring
  noun (neuter)
  From root arc (to worship).
  Root: arc (class 1)

रतः (rataḥ) - devoted to, engaged in (delighted in, engaged in, attached to)

(adjective)

Nominative, masculine, singular of rata

rata - delighted, pleased, fond of, engaged in, attached to

Past Passive Participle

Derived from the root ram (to delight, to enjoy).

Root: ram (class 1)

त्रिरात्रोपोषितः (trirātropoṣitaḥ) - one who has fasted for three nights

(adjective)

Nominative, masculine, singular of trirātropoṣita

trirātropoṣita - one who has fasted for three nights; having observed a fast for three nights

Compound type : bahuvrīhi/tatpuruṣa (tri+rātra+upoṣita)

• tri – three
  numeral
• rātra – night (often used as a suffix for duration of nights)
  noun (neuter)
• upoṣita – fasted, abstained from food
  adjective (masculine)
  Past Passive Participle
  Derived from the root vas (to dwell) with upasarga upa, meaning 'to fast' in this context.
  Prefix: upa
  Root: vas (class 1)

राजन् (rājan) - O King

(noun)

Vocative, masculine, singular of rājan

rājan - king, ruler

अग्निष्टोमफलम् (agniṣṭomaphalam) - the merit obtained from performing the Agniṣṭoma sacrifice (the fruit or result of the Agniṣṭoma sacrifice)

(noun)

Accusative, neuter, singular of agniṣṭomaphala

agniṣṭomaphala - fruit of the Agniṣṭoma; result of the Agniṣṭoma sacrifice

Compound type : tatpuruṣa (agniṣṭoma+phala)

• agniṣṭoma – name of an important Vedic sacrifice
  proper noun (masculine)
• phala – fruit, result, consequence, reward
  noun (neuter)

लभेत् (labhet) - should obtain, may obtain, would obtain

(verb)

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

Root: labh (class 1)