योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-138, verse-16

सह चित्तेन तास्तस्य समस्तेन्द्रियवृत्तयः ।
हृत्कोशमविशञ्छन्नाः कूर्मस्येवाङ्गसंधयः ॥ १६ ॥

saha cittena tāstasya samastendriyavṛttayaḥ ,
hṛtkośamaviśañchannāḥ kūrmasyevāṅgasaṃdhayaḥ 16

16. saha cittena tāḥ tasya samasta-indriya-vṛttayaḥ
hṛt-kośam aviśan channāḥ kūrmasya iva aṅga-sandhayaḥ

16. tasya tāḥ samasta-indriya-vṛttayaḥ cittena saha hṛt-kośam
channāḥ aviśan kūrmasya aṅga-sandhayaḥ iva (channāḥ aviśan)

16. Along with his mind (citta), all his sense activities (indriyavṛtti) entered the heart's sheath, becoming concealed, just as a tortoise retracts its limbs into its shell.

Words meanings summery:

• सह (saha) - with, along with, together with

• चित्तेन (cittena) - by the mind, with the mind

• ताः (tāḥ) - those (feminine plural)

• तस्य (tasya) - his, of him, of that

• समस्त-इन्द्रिय-वृत्तयः (samasta-indriya-vṛttayaḥ) - all the activities of the senses, all sense faculties

• हृत्-कोशम् (hṛt-kośam) - into the sheath/cavity of the heart

• अविशन् (aviśan) - they entered

• छन्नाः (channāḥ) - hidden, covered, concealed

• कूर्मस्य (kūrmasya) - of a tortoise

• इव (iva) - like, as, as if

• अङ्ग-सन्धयः (aṅga-sandhayaḥ) - the joints of the limbs, the limbs (in context of retraction)

Words meanings and morphology

सह (saha) - with, along with, together with

(indeclinable)

चित्तेन (cittena) - by the mind, with the mind

(noun)

Instrumental, neuter, singular of citta

citta - mind, consciousness, thought, intellect

Past Passive Participle

Derived from √cit (to perceive, observe, understand) + -ta

Root: cit (class 1)

Note: Used with 'saha'.

ताः (tāḥ) - those (feminine plural)

(pronoun)

Nominative, feminine, plural of tad

tad - that, those

Note: Refers to samasta-indriya-vṛttayaḥ.

तस्य (tasya) - his, of him, of that

(pronoun)

Genitive, masculine, singular of tad

tad - that, he, it

समस्त-इन्द्रिय-वृत्तयः (samasta-indriya-vṛttayaḥ) - all the activities of the senses, all sense faculties

(noun)

Nominative, feminine, plural of samasta-indriya-vṛtti

samasta-indriya-vṛtti - all the activities of the senses; all sense faculties

Compound type : tatpurusha (samasta+indriya+vṛtti)

• samasta – all, entire, complete, collective
  adjective (masculine)
  Past Passive Participle
  Derived from sam-√as (to throw, be) in a collective sense
  Prefix: sam
  Root: as (class 2)
• indriya – sense organ, faculty, power
  noun (neuter)
• vṛtti – activity, function, mode of being, modification
  noun (feminine)
  Derived from √vṛt (to turn, exist) + -ti
  Root: vṛt (class 1)

Note: Subject of 'aviśan'.

हृत्-कोशम् (hṛt-kośam) - into the sheath/cavity of the heart

(noun)

Accusative, masculine, singular of hṛt-kośa

hṛt-kośa - heart-sheath, heart's cavity, pericardium

Compound type : tatpurusha (hṛd+kośa)

• hṛd – heart, mind, soul
  noun (neuter)
• kośa – sheath, casing, treasury, bud, cavity, cup
  noun (masculine)

Note: Indicates destination.

अविशन् (aviśan) - they entered

(verb)

3rd person , plural, active, past imperfect (laṅ) of viś

Imperfect

Imperfect 3rd person plural, root viś

Root: viś (class 6)

छन्नाः (channāḥ) - hidden, covered, concealed

(participle)

Nominative, feminine, plural of channa

channa - hidden, covered, concealed, secret

Past Passive Participle

Derived from √chad (to cover, conceal) + -na

Root: chad (class 1)

Note: Modifies 'samasta-indriya-vṛttayaḥ'.

कूर्मस्य (kūrmasya) - of a tortoise

(noun)

Genitive, masculine, singular of kūrma

kūrma - tortoise, turtle

इव (iva) - like, as, as if

(indeclinable)

अङ्ग-सन्धयः (aṅga-sandhayaḥ) - the joints of the limbs, the limbs (in context of retraction)

(noun)

Nominative, masculine, plural of aṅga-sandhi

aṅga-sandhi - limb-joint, connection of limbs

Compound type : tatpurusha (aṅga+sandhi)

• aṅga – limb, body part, member
  noun (neuter)
• sandhi – joint, union, connection, treaty
  noun (masculine)
  From sam-√dhā (to put together)
  Prefix: sam
  Root: dhā (class 3)

Note: Subject of the simile, implied 'aviśan' or 'became hidden'.