योगवासिष्ठः yogavāsiṣṭhaḥ - book-6, chapter-63, verse-4

स रुद्रो रुद्रभवने विजहार यथेच्छया ।
तैस्तैः शिवपुराचारैर्गणकोटिगरिष्ठया ॥ ४ ॥

sa rudro rudrabhavane vijahāra yathecchayā ,
taistaiḥ śivapurācārairgaṇakoṭigariṣṭhayā 4

4. saḥ rudraḥ rudrabhavane vijahāra yathecchayā
taiḥ taiḥ śivapurācāraiḥ gaṇakoṭigariṣṭhayā

4. saḥ rudraḥ rudrabhavane yathecchayā taiḥ taiḥ
śivapurācāraiḥ gaṇakoṭigariṣṭhayā vijahāra

4. That Rudra disported in Rudra's abode as he pleased, engaging in various ancient Śaiva practices, accompanied by his most excellent crore of attendants (Gaṇas).

Words meanings summery:

• सः (saḥ) - He (Rudra) (that, he)

• रुद्रः (rudraḥ) - Rudra, the Roarer

• रुद्रभवने (rudrabhavane) - in Rudra's abode, in Śiva's dwelling

• विजहार (vijahāra) - he disported, he enjoyed himself, he roamed about

• यथेच्छया (yathecchayā) - as one wishes, according to desire

• तैः (taiḥ) - by those

• तैः (taiḥ) - those very (for emphasis) (by those)

• शिवपुराचारैः (śivapurācāraiḥ) - by ancient Śaiva practices/customs

• गणकोटिगरिष्ठया (gaṇakoṭigariṣṭhayā) - by the most excellent crore of Gaṇas

Words meanings and morphology

सः (saḥ) - He (Rudra) (that, he)

(pronoun)

Nominative, masculine, singular of tad

tad - that, he/she/it

रुद्रः (rudraḥ) - Rudra, the Roarer

(proper noun)

Nominative, masculine, singular of rudra

rudra - Rudra (a Vedic deity, later identified with Śiva), the roamer, the formidable

Root: rud (class 2)

रुद्रभवने (rudrabhavane) - in Rudra's abode, in Śiva's dwelling

(noun)

Locative, neuter, singular of rudrabhavana

rudrabhavana - Rudra's abode, Śiva's dwelling

Compound type : ṣaṣṭhī-tatpuruṣa (rudra+bhavana)

• rudra – Rudra, Śiva
  proper noun (masculine)
  Root: rud (class 2)
• bhavana – abode, dwelling, house
  noun (neuter)
  agent noun
  Derived from root bhū (to be) with suffix -ana.
  Root: bhū (class 1)

विजहार (vijahāra) - he disported, he enjoyed himself, he roamed about

(verb)

3rd person , singular, active, perfect (lit) of vijahāra

Perfect Active

Root hṛ with prefixes vi- and ā-, meaning to roam, sport, enjoy.

Prefixes: vi+ā

Root: hṛ (class 1)

यथेच्छया (yathecchayā) - as one wishes, according to desire

(indeclinable)

Adverbial compound formed from yathā (as) and icchā (desire), using the instrumental singular of icchā.

Compound type : avyayībhāva (yathā+icchā)

• yathā – as, according to
  indeclinable
• icchā – wish, desire, will
  noun (feminine)
  Root: iṣ (class 4)

Note: Instrumental singular form of 'icchā' used adverbially within the compound.

तैः (taiḥ) - by those

(pronoun)

Instrumental, masculine, plural of tad

tad - that, he/she/it

Note: Refers to the practices (ācāraiḥ).

तैः (taiḥ) - those very (for emphasis) (by those)

(pronoun)

Instrumental, masculine, plural of tad

tad - that, he/she/it

Note: Repetition emphasizes 'those very' or 'various' practices.

शिवपुराचारैः (śivapurācāraiḥ) - by ancient Śaiva practices/customs

(noun)

Instrumental, masculine, plural of śivapurācāra

śivapurācāra - ancient practices or customs of Śiva

Compound type : ṣaṣṭhī-tatpuruṣa (śiva+purācāra)

• śiva – Śiva, auspicious
  proper noun (masculine)
• purācāra – ancient custom, old practice
  noun (masculine)

गणकोटिगरिष्ठया (gaṇakoṭigariṣṭhayā) - by the most excellent crore of Gaṇas

(adjective)

Instrumental, feminine, singular of gaṇakoṭigariṣṭha

gaṇakoṭigariṣṭha - most excellent crore of Gaṇas

Compound type : karmadhāraya (gaṇakoṭi+gariṣṭha)

• gaṇakoṭi – a crore of Gaṇas, ten million attendants
  noun (feminine)
• gariṣṭha – most excellent, heaviest, most venerable
  adjective (feminine)
  superlative
  Superlative degree of 'guru' (heavy, venerable).

Note: Agrees with an implied feminine noun or describes the quality of the 'gaṇakoṭi'.