महाभारतः mahābhārataḥ - book-5, chapter-105, verse-8

प्रतिश्रुत्य करिष्येति कर्तव्यं तदकुर्वतः ।
मिथ्यावचनदग्धस्य इष्टापूर्तं प्रणश्यति ॥८॥

8. pratiśrutya kariṣyeti kartavyaṁ tadakurvataḥ ,
mithyāvacanadagdhasya iṣṭāpūrtaṁ praṇaśyati.

8. pratiśrutya kariṣye iti kartavyam tat akurvataḥ
mithyāvacanadagdhasya iṣṭāpūrtam praṇaśyati

8. If someone promises, 'I will do this duty (kartavya),' but then fails to perform it, their merits from religious sacrifices (iṣṭa) and charitable deeds (pūrta) are consumed by their false words and thus utterly lost.

Words meanings summery:

• प्रतिश्रुत्य (pratiśrutya) - having promised, having assented

• करिष्ये (kariṣye) - I will do, I shall perform

• इति (iti) - thus, in this manner, marking direct speech

• कर्तव्यम् (kartavyam) - duty, what should be done, an obligation

• तत् (tat) - that, that (duty)

• अकुर्वतः (akurvataḥ) - of one not doing, of one who fails to perform

• मिथ्यावचनदग्धस्य (mithyāvacanadagdhasya) - of one whose merits are destroyed due to breaking promises with false words (of one scorched or burned by false words or promises)

• इष्टापूर्तम् (iṣṭāpūrtam) - merits from sacrifices and charitable deeds

• प्रणश्यति (praṇaśyati) - perishes, is destroyed, is lost

Words meanings and morphology

प्रतिश्रुत्य (pratiśrutya) - having promised, having assented

(indeclinable)

absolutive

Formed from the root śru (to hear) with prefix prati-, signifying 'having heard in response' or 'having promised'.

Prefix: prati

Root: śru (class 5)

करिष्ये (kariṣye) - I will do, I shall perform

(verb)

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

future tense, 1st person singular, middle voice

From root kṛ, future tense form. The 'e' ending indicates ātmanepada (middle voice) for the 1st person singular.

Root: kṛ (class 8)

इति (iti) - thus, in this manner, marking direct speech

(indeclinable)

कर्तव्यम् (kartavyam) - duty, what should be done, an obligation

(noun)

Accusative, neuter, singular of kartavya

kartavya - to be done, fit to be done, duty, obligation, task

gerundive

Formed from root kṛ (to do) with suffix tavya.

Root: kṛ (class 8)

तत् (tat) - that, that (duty)

(pronoun)

Accusative, neuter, singular of tad

tad - that, he, she, it

Note: Refers to 'kartavyam'.

अकुर्वतः (akurvataḥ) - of one not doing, of one who fails to perform

(adjective)

Genitive, masculine, singular of akurvat

akurvat - not doing, not performing, failing to act

present active participle

Formed from the negative prefix a- and kurvat (present active participle of kṛ, to do).

Root: kṛ (class 8)

मिथ्यावचनदग्धस्य (mithyāvacanadagdhasya) - of one whose merits are destroyed due to breaking promises with false words (of one scorched or burned by false words or promises)

(adjective)

Genitive, masculine, singular of mithyāvacanadagdha

mithyāvacanadagdha - burned by false words, scorched by untrue statements

Bahuvrīhi compound, meaning 'he by whom false words (mithyāvacana) have caused burning (dagdha) of something (like merits)'.

Compound type : bahuvrīhi (mithyāvacana+dagdha)

• mithyāvacana – false word, lie, untruthful statement
  noun (neuter)
  Compound of mithyā (falsely, wrongly) and vacana (word, speech).
• dagdha – burned, scorched, consumed, destroyed
  adjective (masculine)
  Past Passive Participle
  From root dah (to burn) with kta suffix.
  Root: dah (class 1)

Note: Agrees with 'akurvataḥ'.

इष्टापूर्तम् (iṣṭāpūrtam) - merits from sacrifices and charitable deeds

(noun)

Nominative, neuter, singular of iṣṭāpūrta

iṣṭāpūrta - a compound term referring to the aggregate of religious offerings (iṣṭa) and charitable works (pūrta)

Dvaṃdva compound of iṣṭa (sacrifices, worship) and pūrta (public works like digging wells, building temples, etc.). Often appears as a neuter singular collective noun.

Compound type : dvaṃdva (iṣṭa+pūrta)

• iṣṭa – sacrificed, worshipped; sacrifice, worship, offering
  noun (neuter)
  Past Passive Participle
  From root yaj (to sacrifice, worship) with kta suffix (irregular formation).
  Root: yaj (class 1)
• pūrta – filled, fulfilled, completed; charitable deeds, public works (e.g., digging wells, building temples, etc.)
  noun (neuter)
  Past Passive Participle
  From root pṛ (to fill, complete) with kta suffix.
  Root: pṛ (class 3)

प्रणश्यति (praṇaśyati) - perishes, is destroyed, is lost

(verb)

3rd person , singular, active, present (laṭ) of praṇaś

present tense, 3rd person singular, active voice

From root naś (to perish) with prefix pra-.

Prefix: pra

Root: naś (class 4)