BhG 3.5

syntax

jātu (ever) kaścit [janaḥ] (whichever person) akarma-kṛt (who is not acting) kṣaṇam api (even for a moment) na hi tiṣṭhati (surely he does not remain).
prakṛti-jaiḥ (by these born from nature) guṇaiḥ (by the guṇas) sarvaḥ hi (everyone indeed) avaśaḥ (helplessly) karma (activity) kāryate (he is caused to act).

grammar

na	–	av. – not;
hi	–	av. – because, just, indeed, surely;
kaś-cit	–	kim-cit sn. 1n.1 m. – someone (from: kim – what?; -cit – indefinitive particle);
kṣaṇam	–	kṣaṇa 2n.1 n. – a moment, twinkling of an eye (from: √kṣan – to hurt, to break);
api	–	av. – although, moreover, besides, even;
jātu	–	av. – at all, ever, once, some day;
tiṣṭhati	–	√sthā (to stand) Praes P 1v.1 – he stays, he remains;
akarma-kṛt	–	a-karma-kṛt 1n.1 m.; yaḥ karma na karoti saḥ – who is not acting (from: √kṛ – to do, karman – activity and its result; -kṛt – suffix indicates a doer);
kāryate	–	√kṛ (to do) Praes. caus. pass. 1v.1 – he is caused to act;
hi	–	av. – because, just, indeed, surely;
avaśaḥ	–	avaśa 1n.1 m. – not being under control, helplessly (from: √vaś – to desire, to subjugate, to command, vaśa – wish, power, control, dominion);
karma	–	karman 2n.1 n. – activity (from: √kṛ – to do);
sarvaḥ	–	sarva sn. 1n.1 m. – all;
prakṛti-jaiḥ	–	prakṛti-ja 3n.3 m. – by these born from nature (from: pra-√kṛ – to produce, prakṛti – nature, primary substance, original cause; √jan – to be born, –ja – suffix: born);
guṇaiḥ	–	guṇa 3n.3 m. – by qualities, virtues, threads (from: √grah – to take);

textual variants

avaśaḥ → svavaśaḥ (fully helplessly);
sarvaḥ prakṛti-jair → sarvaiḥ prakṛti-jair /sarva-prakṛti-jair (by all these born from nature);

Śāṃkara

The key:
an excerpt from the commented verse
quotes from the scriptures
starting polemic

The ignorant are swayed by Nature. For what reason, then, does a person not attain perfection, i.e., freedom from activity, by mere renunciation unaccompanied with knowledge ? The reason thus asked for is given as follows:		kasmāt punaḥ kāraṇāt karma-saṃnyāsa-mātrād eva kevalāt jñāna-rahitāt siddhiṃ naiṣkarmya-lakṣaṇāṃ puruṣo nādhigacchati iti hetv-ākāṅkṣāyām āha –
None, verily, even for an instant, ever remains doing no action; for every one is driven helpless to action by the energies born of Nature		na hi kaścit kṣaṇam api jātu tiṣṭhaty akarmakṛt | kāryate hy avaśaḥ karma sarvaḥ prakṛtijair guṇaiḥ ||3.5||
The energies (guṇas) are three, Sattva, Rajas and Tamas.		na hi yasmāt kṣaṇam api kālaṃ jātu kadācit kaścit tiṣṭhaty akarma-kṛt san | kasmāt? kāryate pravartyate hi yasmād avaśa evāsvatantra eva karma sarvaḥ prāṇī prakṛti-jaiḥ prakṛtito jātaiḥ sattva-rajas-tamobhiḥ guṇaiḥ |
‚Every one‚ means every living being that is ignorant, (ajña), who knows not (the Self); for, it is said (of a wise man ” that he is one) „who is unshaken by the energies” (BhG14.23). Since the Sankhyas have been distinguished from the Yogins (BhG 3.3), the Karma-yoga, devotion to action, is indeed meant for the ignorant only, not for the wise.		ajña iti vākya-śeṣaḥ, yato vakṣyati guṇair yo na vicālyate (BhG 14.23) iti | sāṃkhyānāṃ pṛthak-karaṇāt ajñānām eva hi karma-yogaḥ, na jñāninām |
As for the wise who are unshaken by the guṇas, and who in themselves are devoid of any change whatever, the Karma-yoga is out of place. And this was explained at length in our comments on 2.21.		jñānināṃ tu guṇair acālyamānānāṃ svataś calanābhāvāt karma-yogo nopapadyate | tathā ca vyākhyātaṃ vedāvināśinaṃ (BhG 2.21) ity atra ||3.5||

Rāmānuja

etad evopapādayati

na hy asmin loke vartamānaḥ puruṣaḥ kaścit kadācid api karmākurvāṇas tiṣṭhati; na kiṃcit karomīti vyavasito ‚pi sarvaḥ puruṣaḥ prakṛtisaṃbhavaiḥ sattvarajastamobhiḥ prācīnakarmānuguṇaṃ pravṛddhair guṇaiḥ svocitaṃ karma prati avaśaḥ kāryate pravartyate / ata uktalakṣaṇena karmayogena prācīnaṃ pāpasaṃcayaṃ nāśayitvā guṇāṃś ca sattvādīn vaśe kṛtvā nirmalāntaḥkaraṇena saṃpādyo jñānayogaḥ

Śrīdhara

karmaṇāṃ ca saṃnyāsas teṣv anāsakti-mātram | na tu svarūpeṇa | aśakyatvād iti | āha na hi kaścid iti | jātu kasyāṃcid apy avasthāyāṃ kṣaṇa-mātram api kaścid api jñāny-ajñāno vā akarma-kṛt karmāṇy akurvāṇo na tiṣṭhati | atra hetuḥ — prakṛtijair svabhāva-prabhavai rāga-dveṣādibhir guṇaiḥ sarvo ‚pi janaḥ karma kāryate | karmaṇi pravartyate | avaśo ‚svatantraḥ san

Madhusūdana

tatra karma-janya-śuddhy-abhāve bahirmukhaḥ | hi yasmāt kṣaṇam api kālaṃ jātu kadācit kaścid apy ajitendriyo ‚karma-kṛt san na tiṣṭhati | api tu laukika-vaidikakarmānuṣṭhāna-vyagra eva tiṣṭhati tasmād aśuddha-cittasya saṃnyāso na sambhavatīty arthaḥ |

kasmāt punar avidvān karmāṇy akurvāṇo na tiṣṭhati | hi yasmāt | sarvaḥ prāṇī citta-śuddhi-rahito ‚vaśo ‚svatantra eva san prakṛtijaiḥ prakṛtito jātair abhivyaktaiḥ kāryākāreṇa sattva-rajas-tamobhiḥ svabhāva-prabhavair vā rāga-dveṣādibhir guṇaiḥ karma laukikaṃ vaidikaṃ vā kāryate | ataḥ karmāṇy akurvāṇo na kaścid api tiṣṭhatīty arthaḥ | yataḥ svābhāvikā guṇāś cālakā ataḥ para-vaśatayā sarvadā karmāṇi kurvato ‚śuddha-buddheḥ sarva-karma-saṃnyāso na sambhavatīti na saṃnyāsa-nibandhanā jñāna-niṣṭhā sambhavatīty arthaḥ

Viśvanātha

kintv aśuddha-cittaḥ kṛta-saṃnyāsaḥ śāstrīyaṃ karma parityajya vyavahārike karmaṇi nimajjatīty āha na hīti | nanu saṃnyāsa eva tasya vaidika-laukika-karma-pravṛttir-virodhī ? tatrāha kāryata iti | avaśo ‚svatantraḥ

Baladeva

aviśuddha-cittaḥ kṛta-vaidika-karma-saṃnyāso laukike ‚pi karmaṇi nimajjatīty āha nahīti | nanu saṃnyāsa eva tasya sarva-karma-virodhīti cet tatrāha kāryata iti | prakṛtijaiḥ svabhāvodbhavair guṇai rāga-dveṣādibhiḥ, kāryate pravartyate avaśaḥ parādhīnaḥ syā