BhG 18.7

syntax

niyatasya tu (of the regulated) karmaṇaḥ (activity) sannyāsaḥ (renunciation) na upapadyate (it is not suitable),
mohāt (out of bewilderment) tasya (its) parityāgaḥ (abandonment) tāmasaḥ (as tamasic) parikīrtitaḥ [asti] (it is proclaimed).

grammar

niyatasya	–	niyata (ni-√yam – to hold back, to regulate) PP 6n.1 m. – of the regulated, of restrained;
tu	–	av. – but, then, or, and;
saṁnyāsaḥ	–	saṁnyāsa 1n.1 m. – laying aside, resignation, renunciation (from: sam-ni-√as – to lay aside, to renounce, to give up);
karmaṇaḥ	–	karman 6n.1 n. – in activity (from: √kṛ – to do);
na	–	av. – not;
upapadyate	–	upa-√pad (to approach, to exist, to be suitable, to attain) Praes. Ā 1v.1 – it is suitable, it exists;
mohāt	–	moha 5n.1 m. – out of bewilderment (from: √muh – to become confused, bewildered, stupefied);
tasya	–	tat sn. 6n.1 m. – its;
parityāgaḥ	–	pari-tyāga 1n.1 m. – leaving, abandonment (from: pari-√tyaj – to abandon, to give up);
tāmasaḥ	–	tāmasa 1n.1 m. – related to tamas, tamasic (from: √tam – to choke, to faint, to perish, to stop; tamas – darkness, gloom, dullness, passivity, one of the three guṇas);
parikīrtitaḥ	–	pari-kīrtita (pari-√kīrt – to praise, to glorify) PP 1n.1 m. – praised, celebrated, proclaimed, known (from: kīrti – fame, glory);

textual variants

tu → ca (and);
mohāt tasya → mohārtasya (suffering out of bewilderment);
parikīrtitaḥ → parikīrtyate (it is proclaimed);

Śāṃkara

tasmād ajñasyādhikṛtasya mumukṣoḥ—
niyatasya tu nityasya saṃnyāsaḥ parityāgaḥ karmaṇo nopapadyate, ajñasya pāvanatvasya iṣṭatvāt | mohād ajñānāt tasya niyatasya parityāgaḥ—niyataṃ cāvaśyaṃ kartavyaṃ tyajyate ceti vipratiṣiddham | ati moha-nimittaḥ parityāgas tāmasaḥ parikīrtitaḥ | mohaś ca tama iti

Rāmānuja

niyatasya nityanaimittikasya mahāyajñādeḥ karmaṇaḥ saṃnyāsaḥ tyāgo nopapadyate, „śarīrayātrāpi ca tena prasiddhyed akarmaṇaḥ” iti śarīrayātrāyā evāsiddheḥ, śarīrayātrā hi yajñaśiṣṭāśanena nirvartyamānā samyagjñānāya prabhavati; anyathā, „te tv aghaṃ bhuñjate pāpāḥ” ity ayajñaśiṣṭāgharūpāśanāpyāyanaṃ manaso viparītajñānāya bhavati / „annamayaṃ hi somya manaḥ” ity annena hi mana āpyāyate / „āhāraśuddhau sattvaśuddhis sattvaśuddhau dhruvā smṛtiḥ / smṛtilambhe sarvagranthīnāṃ vipramokṣaḥ // BhGR_18.” iti brahmasākṣātkārarūpaṃ jñānam āhāraśuddhyāyattaṃ śrūyate / tasmān mahāyajñādinityanaimittikaṃ karma ā prayāṇād brahmajñānāyaivopādeyam iti tasya tyāgo nopapadyate / evaṃ jñānotpādinaḥ karmaṇo bandhakatvamohāt parityāgas tāmasaḥ parikīrtitaḥ / tamomūlas tyāgas tāmasaḥ / tamaḥkāryājñānamūlatvena tyāgasya tamomūlatvam / tamo hy ajñānasya mūlaṃ, „pramādamohau tamaso bhavato ‚jñānam eva ca” ity atroktam / ajñānaṃ tu jñānavirodhi viparītajñānam; tathā ca vakṣyate, „adharmaṃ dharmam iti yā manyate tamasāvṛtā / sarvārthān viparītāṃś ca buddhiḥ sā pārtha tāmasī” iti / ato nityanaimittikādeḥ karmaṇas tyāgo viparītajñānamūla evetyarthaḥ

Śrīdhara

pratijñātaṃ tyāgasya traividhyam idānīṃ darśayati niyatasyeti tribhiḥ | kāmyasya karmaṇo bandhakatvāt sannyāso yuktam | niyatasya tu nityasya punaḥ karmaṇaḥ sannyāsas tyāgo nopapadyate | sattva-śuddhi-dvārā mokṣa-hetutvāt | atas tasya parityāga upādeyatve ‚pi tyājyam ity evaṃ lakṣaṇān mohād eva bhavet | sa ca mohasya tāmasatvāt tāmasaḥ parikīrtitaḥ

Viśvanātha

prakrāntasya trividha-tyāgasya tāmasaṃ bhedam āha niyatasya nityasya | mohāt śāstra-tātparyājñānāt | sannyāsī kāmya-karmaṇy āvaśyakatvābhāvāt parityajatu nāma, nityasya tu karmaṇas tyāgo nopapadyate iti tu śabdārthaḥ | mohād ajñānāt | tāmasa iti tāmasa-tyāgasya phalam ajñāna-prāptir eva | na tv abhīpsita-jñāna-prāptir iti bhāvaḥ

Baladeva

pratijñātaṃ tyāga-traividhyam āha niyatasyeti tribhiḥ | kāmyasya karmaṇo bandhakatvāt tyāgo yuktaḥ | niyatasya nitya-naimittikasya mahā-yajñādeḥ karmaṇaḥ sannyāsas tyāgo nopapadyate | ātmoddeśād viśīrṇādivad antargata-jñānasya tasya mocakatvād dehayātrā-sādhakatvāc ca tat-tyāgo na yuktaḥ | tena hi devatā-bhagavad-vibhūtir arcatāṃ tac-cheṣaiḥ pūtaiḥ siddhā deha-yātrā tattva-jñānāya sampadyate | vaiparītye pūrvam abhihitaṃ nityataṃ kuru karma tvam ity ādibhis tṛtīyae tasyāpi mohād bandhakam idam ity ajñānāt paritaḥ svarūpeṇa tyāgas tāmaso bhavati – mohasya tamo-dharmatvāt