महाभारतः mahābhārataḥ - book-13, chapter-92, verse-19

मासार्धे कृष्णपक्षस्य कुर्यान्निवपनानि वै ।
पुष्टिरायुस्तथा वीर्यं श्रीश्चैव पितृवर्तिनः ॥१९॥

19. māsārdhe kṛṣṇapakṣasya kuryānnivapanāni vai ,
puṣṭirāyustathā vīryaṁ śrīścaiva pitṛvartinaḥ.

19. māsārdhe kṛṣṇapakṣasya kuryāt nivapanāni vai
puṣṭiḥ āyuḥ tathā vīryam śrīḥ ca eva pitṛvartinaḥ

19. kṛṣṇapakṣasya māsārdhe nivapanāni vai kuryāt
pitṛvartinaḥ puṣṭiḥ āyuḥ tathā vīryam śrīḥ ca eva

19. One should indeed perform ancestral offerings (nivapanāni) in the middle of the dark fortnight of the month. Prosperity, longevity, vigor, and glory certainly accrue to those who make these offerings to the ancestors.

Words meanings summery:

• मासार्धे (māsārdhe) - in the middle of the month (referring to the dark fortnight) (in half a month, in the middle of the month)

• कृष्णपक्षस्य (kṛṣṇapakṣasya) - of the dark fortnight

• कुर्यात् (kuryāt) - one should perform, one may do

• निवपनानि (nivapanāni) - ancestral offerings, rites performed for ancestors (offerings, oblations, ancestral rites)

• वै (vai) - indeed, certainly, verily (an emphasizing particle)

• पुष्टिः (puṣṭiḥ) - nourishment, prosperity, growth

• आयुः (āyuḥ) - life, longevity

• तथा (tathā) - and, similarly, thus

• वीर्यम् (vīryam) - vigor, strength, heroism, semen

• श्रीः (śrīḥ) - prosperity, wealth, glory, beauty, divine grace

• च (ca) - and

• एव (eva) - only, just, indeed, certainly

• पितृवर्तिनः (pitṛvartinaḥ) - to those who perform rites for ancestors or are devoted to ancestors (belonging to ancestors, performing ancestral rites, ancestor-devoted)

Words meanings and morphology

मासार्धे (māsārdhe) - in the middle of the month (referring to the dark fortnight) (in half a month, in the middle of the month)

(noun)

Locative, neuter, singular of māsārdha

māsārdha - half a month, mid-month

Compound type : tatpurusha (māsa+ardha)

• māsa – month
  noun (masculine)
  Root: mā
• ardha – half, part
  noun (masculine)
  Root: ṛdh

कृष्णपक्षस्य (kṛṣṇapakṣasya) - of the dark fortnight

(noun)

Genitive, masculine, singular of kṛṣṇapakṣa

kṛṣṇapakṣa - dark fortnight of the lunar month

Compound type : karmadharaya (kṛṣṇa+pakṣa)

• kṛṣṇa – dark, black
  adjective (masculine)
  Root: kṛṣ
• pakṣa – fortnight, wing, side, party
  noun (masculine)
  Root: pakṣ

कुर्यात् (kuryāt) - one should perform, one may do

(verb)

3rd person , singular, active, optative (vidhi liṅ) of kṛ

Root: kṛ (class 8)

निवपनानि (nivapanāni) - ancestral offerings, rites performed for ancestors (offerings, oblations, ancestral rites)

(noun)

Accusative, neuter, plural of nivapana

nivapana - offering, oblation, ancestral rite

From ni-vap (to sow, to scatter, to offer)

Prefix: ni

Root: vap (class 1)

वै (vai) - indeed, certainly, verily (an emphasizing particle)

(indeclinable)

पुष्टिः (puṣṭiḥ) - nourishment, prosperity, growth

(noun)

Nominative, feminine, singular of puṣṭi

puṣṭi - nourishment, prosperity, growth, thriving

From root puṣ (to thrive, nourish)

Root: puṣ (class 4)

आयुः (āyuḥ) - life, longevity

(noun)

Nominative, neuter, singular of āyus

āyus - life, duration of life, longevity

Root: i (class 2)

तथा (tathā) - and, similarly, thus

(indeclinable)

वीर्यम् (vīryam) - vigor, strength, heroism, semen

(noun)

Nominative, neuter, singular of vīrya

vīrya - vigor, strength, energy, heroism, virility, semen

Root: vīr

श्रीः (śrīḥ) - prosperity, wealth, glory, beauty, divine grace

(noun)

Nominative, feminine, singular of śrī

śrī - prosperity, wealth, glory, beauty, divine grace, goddess Lakṣmī

Root: śrī

च (ca) - and

(indeclinable)

एव (eva) - only, just, indeed, certainly

(indeclinable)

पितृवर्तिनः (pitṛvartinaḥ) - to those who perform rites for ancestors or are devoted to ancestors (belonging to ancestors, performing ancestral rites, ancestor-devoted)

(adjective)

Dative, masculine, plural of pitṛvartin

pitṛvartin - devoted to ancestors, honoring ancestors, pertaining to ancestors

Compound type : tatpurusha (pitṛ+vartin)

• pitṛ – father, ancestor
  noun (masculine)
• vartin – being, existing, abiding, acting, relating to
  adjective (masculine)
  agent noun/adjective from root vṛt
  Derived from root vṛt with -in suffix.
  Root: vṛt (class 1)

Note: Can be dative or genitive plural for those belonging to ancestors. Here, implies 'to' or 'for' them.