महाभारतः mahābhārataḥ - book-13, chapter-16, verse-29

देवासुरमनुष्याणां यच्च गुह्यं सनातनम् ।
गुहायां निहितं ब्रह्म दुर्विज्ञेयं सुरैरपि ॥२९॥

29. devāsuramanuṣyāṇāṁ yacca guhyaṁ sanātanam ,
guhāyāṁ nihitaṁ brahma durvijñeyaṁ surairapi.

29. devāsuramanuṣyāṇām ca guhyam sanātanam
guhāyām nihitam brahma durvijñeyam suraiḥ api

29. ca yat devāsuramanuṣyāṇām guhyam sanātanam
guhāyām nihitam brahma suraiḥ api durvijñeyam

29. And that which is a secret and eternal truth (sanātana) for gods, asuras, and humans—the ultimate reality (brahman) hidden in the secret chamber (guhā)—is difficult for even the gods to know.

Words meanings summery:

• देवासुरमनुष्याणाम् (devāsuramanuṣyāṇām) - of gods, asuras, and humans

• च (ca) - and, also

• गुह्यम् (guhyam) - secret, mysterious, hidden

• सनातनम् (sanātanam) - eternal, ancient, perpetual

• गुहायाम् (guhāyām) - in the secret chamber of the heart (in the cave, in the secret place)

• निहितम् (nihitam) - placed, hidden, deposited

• ब्रह्म (brahma) - the Absolute, the Supreme Reality

• दुर्विज्ञेयम् (durvijñeyam) - difficult to know, inscrutable, unknowable

• सुरैः (suraiḥ) - by the gods

• अपि (api) - even, also, too

Words meanings and morphology

देवासुरमनुष्याणाम् (devāsuramanuṣyāṇām) - of gods, asuras, and humans

(noun)

Genitive, masculine, plural of devāsuramanuṣya

devāsuramanuṣya - gods, asuras, and humans (collectively)

Compound type : dvandva (deva+asura+manuṣya)

• deva – god, deity
  noun (masculine)
• asura – anti-god, demon, asura
  noun (masculine)
• manuṣya – human, man
  noun (masculine)

च (ca) - and, also

(indeclinable)

गुह्यम् (guhyam) - secret, mysterious, hidden

(adjective)

Nominative, neuter, singular of guhya

guhya - secret, hidden, mysterious, that which is to be hidden

Gerundive

Derived from root 'guh' with suffix -ya.

Root: guh (class 1)

सनातनम् (sanātanam) - eternal, ancient, perpetual

(adjective)

Nominative, neuter, singular of sanātana

sanātana - eternal, ancient, perpetual, primeval

गुहायाम् (guhāyām) - in the secret chamber of the heart (in the cave, in the secret place)

(noun)

Locative, feminine, singular of guhā

guhā - cave, cavern, secret place, heart (metaphorically)

Root: guh (class 1)

निहितम् (nihitam) - placed, hidden, deposited

(adjective)

Nominative, neuter, singular of nihita

nihita - placed, put, laid down, hidden, deposited

Past Passive Participle

Prefix: ni

Root: dhā (class 3)

ब्रह्म (brahma) - the Absolute, the Supreme Reality

(noun)

Nominative, neuter, singular of brahman

brahman - the Absolute, the Ultimate Reality, the Universal Spirit

दुर्विज्ञेयम् (durvijñeyam) - difficult to know, inscrutable, unknowable

(adjective)

Nominative, neuter, singular of durvijñeya

durvijñeya - difficult to know, incomprehensible, inscrutable

Compound type : prādi tatpuruṣa (dur+vijñeya)

• dur – bad, difficult, ill, hard
  prefix
• vijñeya – to be known, to be understood
  adjective (neuter)
  Gerundive
  Derived from root 'jñā' with prefix 'vi' and suffix -ya.
  Prefix: vi
  Root: jñā (class 9)

सुरैः (suraiḥ) - by the gods

(noun)

Instrumental, masculine, plural of sura

sura - god, deity

अपि (api) - even, also, too

(indeclinable)