BhG 3.35

syntax

sv-anuṣṭhitāt (than well performed) para-dharmāt (than another’s duty) viguṇaḥ (defective) sva-dharmaḥ (own’s own duty) śreyān (better) [asti] (it is).
sva-dharme (in one’s own duty) nidhanam (death) śreyaḥ (better) [asti] (it is).
para-dharmaḥ (another’s duty) bhayāvahaḥ (bringing fear) [asti] (it is).

grammar

śreyān	–	śreyas 1n.1 m. – better, higher, perfect, the auspiciousness, the welfare (comparative of: śrī – śreyas, śreṣṭha);
sva-dharmaḥ	–	sva-dharma 1n.1 m.; TP: svasya dharma iti – own duties (from: sva – own; √dhṛ – to hold);
viguṇaḥ	–	vi-guṇa 1n.1 m. – defective, bad, faulty (from: vi – prefix: apart, off, without; √grah – to take, guṇa – quality, virtue, thread);
para-dharmāt	–	para-dharma 5n.1 m.; TP: parasya dharmād iti – than another’s duty (from: para – another, strange; √dhṛ – to hold);
svanuṣṭhitāt	–	su-anu-ṣṭhita (anu-√sthā – to follow, to practise) PP 5n.1 m. – than well performed;
sva-dharme	–	sva-dharma 7n.1 m.; TP: svasya dharma iti – in own duties (from: sva – own; √dhṛ – to hold);
nidhanam	–	nidhana 1n.1 n. – end, death;
śreyaḥ	–	śreyas 1n.1 n. – better, higher, perfect, the auspiciousness, the welfare (comparative of: śrī – śreyas, śreṣṭha);
para-dharmaḥ	–	para-dharma 1n.1 m.; TP: parasya dharma iti – another’s duty (from: para – another, strange; √dhṛ – to hold);
bhayāvahaḥ	–	bhaya-āvaha 1n.1 m.; ya bhayam āvahati saḥ – bringing fear, dangerous (from: √bhī – to scare, bhaya – fear; ā-√vah – to bring, āvaha – bringing, inviting);

textual variants

para-dharmo bhayāvahaḥ → para-dharmodayād api (even than elevation in another’s duty);

Śāṃkara

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

Now, the man who is led by love and aversion may misunderstand the Teaching; he may think that one man may follow the duty (dharma) of another because the latter is also a duty. But it is not right to think so:		tatra rāga-dveṣa-prayukto manyate śāsrārtham apy anyathā para-dharmo ’pi dharmatvād anuṣṭheya eva iti, tad asat —
Better one’s own duty, though devoid of merit, than the duty of another well discharged. Better is death in one’s own duty; the duty of another is productive of danger.		śreyān sva-dharmo viguṇaḥ para-dharmāt svanuṣṭhitāt | sva-dharme nidhanaṃ śreyaḥ para-dharmo bhayāvahaḥ ||3.35||
For a man to die doing his own duty though devoid of merit is better than for him to live doing the duty of another though perfectly performed. For, the duty of another leads to danger, such as hell (naraka).		śreyān praśasyataraḥ svo dharmaḥ sva-dharmo viguṇo ’pi vigata-guṇo ’pi anuṣṭhīyamānaḥ para-dharmāt svanuṣṭhitāt sādguṇyena saṃpāditād api | sva-dharme sthitasya nidhanaṃ maraṇam api śreyaḥ para-dharme sthitasya jīvitāt | kasmāt? para-dharmaḥ bhayāvahaḥ narakādi-lakṣaṇaṃ bhayam āvahatīti yataḥ ||3.35||

Rāmānuja

ataḥ suśakatayā svadharmabhūtaḥ karmayogo viguṇo ‚py apramādagarbhaḥ prakṛtisaṃsṛṣṭasya duśśakatayā paradharmabhūtāj jñānayogāt saguṇād api kiṃcit kālam anuṣṭhitāt sapramādāc chreyān; svenaivopādātuṃ yogyatayā svadharmabhūte karmayoge vartamānasyaikasmin janmany aprāptaphalatayā nidhanam api śreyaḥ, anantarāyahatatayānantarajanmany api avyākulakarmayogārambhasaṃbhavāt / prakṛtisaṃsṛṣṭasya svenaivopādātum aśakyatayā paradharmabhūto jñānayogaḥ pramādagarbhatayā bhayāvahaḥ

Śrīdhara

tarhi sva-dharmasya yuddhāder duḥkha-rūpasya yathāvat kartum aśakyatvāt para-dharmasya cāhiṃsādeḥ sukaratvād dharmatvāviśeṣāc ca tatra pravartitum icchantaḥ praty āha śreyān iti | kiṃcid aṅga-hīno ‚pi sva-dharmaḥ śreyān praśasyataraḥ | svanuṣṭhitāt sakalāṅga-sampūrtyā kṛtād api para-dharmāt sakāśāt | tatra hetuḥ – sva-dharme yuddhādau pravartamānasya nidhanaṃ maraṇam api śreṣṭhaṃ svargādi-prāpakatvāt | para-dharmas tu bhayāvaho niṣiddhatvena naraka-prāpakatvāt

Madhusūdana

nanu svābhāvika-rāga-dveṣa-prayukta-paśv-ādi-sādhāraṇa-pravṛtti-prahāṇena śāstrīyam eva karma kartavyaṃ cet tarhi yat sukaraṃ bhikṣāśanādi tad eva kriyatāṃ kim ati-duḥkhāvahena yuddhenety ata āha śreyān iti | śreyān praśasyataraḥ sva-dharmo yaṃ varṇāśramaṃ vā prati yo vihitaḥ sa tasya sva-dharmo viguṇo ‚pi sarvāṅgopasaṃhāram antareṇa kṛto ‚pi para-dharmāt svaṃ praty avihitāt svanuṣṭhitāt sarvāṅgopasaṃhāreṇa sampāditād api | na hi vedātirikta-māna-gamyo dharmaḥ, yena para-dharme ‚py anuṣṭheyo dharmatvāt sva-dharmavad ity anumānaṃ tatra mānaṃ syāt | codana-lakṣaṇo ‚rtho dharmaḥ iti nyāyāt | ataḥ sva-dharme kiṃcid aṅga-hīne ‚pi sthitasya nidhanaṃ maraṇam api śreyaḥ praśasyataraṃ para-dharma-sthasya jīvitād api | sva-dharma-sthasya nidhanaṃ hīha-loke kīrtyāvahaṃ para-loke ca svargādi-prāpakam | para-dharmas tu ihākīrti-karatvena paratra naraka-pradatvena ca bhayāvaho yato ‚to rāga-dveṣādi-prayukta-svābhāvika-pravṛttivat para-dharmo ‚pi heya evety arthaḥ |

evaṃ tāvad bhagavan-matāṅgīkāriṇāṃ śreyaḥ-prāptis tad-anaṅgīkāriṇāṃ ca śreyo-mārga-bhraṣṭatvam uktam | śreyo-mārga-bhraṃśena phalābhisandhi-pūrvaka-kāmya-karmācaraṇe ca kevala-pāpa-mātrācaraṇe ca bahūni kāraṇāni kathitāni ye tv etad abhyasūyanta ity ādinā | tatrāyaṃ saṅgraha-ślokaḥ –

śraddhā-hānis tathāsūyā duṣṭa-cittatvam ūḍhate |
prakṛter vaśa-vartitvaṃ rāga-dveṣau ca puṣkalau |
para-dharma-rucitvaṃ cety uktā durmārga-vāhakāḥ |

Viśvanātha

tataś ca yuddha-rūpasya yathāvad rāga-dveṣādi-rāhityena kartum aśakyatvāt para-dharmasya cāhiṃsādeḥ sukaratvād dharmatvāviśeṣāc ca tatra pravartitum icchantaṃ praty āha śreyān iti | viguṇaḥ kiṃcid doṣa-viśiṣṭo ‚pi samyag anuṣṭhātum aśakyo ‚pi para-dharmāt svanuṣṭhitāt sādhv evānuṣṭhātuṃ śakyād api sarva-guṇa-pūrṇād api sakāśāt śreyān | tatra hetuḥ – svadharma ity ādi |

vidharmaḥ para-dharmaś ca
ābhāsa upamā chalaḥ |
adharma-śākhāḥ pañcemā
dharma-jño ‚dharmavat tyajet || [BhP 7.15.12] iti saptamokteḥ

Baladeva

nanu sva-prakṛti-nirmitāṃ rāga-dveṣa-mayīṃ paśv-ādi-sādhāraṇīṃ pravṛttiṃ vihāya śāstrokteṣu dharmeṣu vartitavyam ity uktam | dharma-hṛd-viśuddhau tādṛśa-pravṛttir nivartena, dharmāś ca yuddhādivad ahiṃsādayo ‚pi śāstreṇoktāḥ | tasmād rāga-dveṣa-rāhityena kartum aśakyād yuddhāder ahiṃsā-śiloñcha-vṛtti-lakṣaṇo dharma uttama iti cet tatrāha śreyān iti |

yasya varṇasyāśramasya ca yo dharmo vedena vihitaḥ, sa ca viguṇaḥ kiṃcid aṅga-vikalo ‚pi svanuṣṭhitā sarvāṅgopasaṃhāreṇācaritād api para-dharmāt śreyān | yathā brāhmaṇasyāhiṃsādiḥ sva-dharmaḥ kṣatriyasya ca yuddhādiḥ | na hi dharmo vedātiriktena pramāṇena gamyate | cakṣur bhinnendriyeṇeva rūpam | yathāha jaiminiḥ – codanā-lakṣaṇo dharmaḥ iti | tatra hetuḥ – svadharme nidhanaṃ maraṇaṃ śreyaḥ pratyavāyābhāvāt para-janmani dharmācaraṇa-sambhavāc ceṣṭa-sādhakam ity arthaḥ | para-dharmas tu bhayāvaho ‚niṣṭa-janakaḥ | taṃ praty avihitatvena pratyavāya-sambhavāt | na ca paraśurāme viśvāmitre cavyabhicāraḥ | tayos tat-tat-kulotpannāv api tat tac-coru-mahimnā tat-karmodayāt | tathāpi vigānaṃ kaṣṭaṃ ca tayoḥ smaryate | ataeva droṇādeḥ kṣātra-dharmo ‚sakṛd vigītaḥ |

nanu daivarātyādeḥ kṣatriyasya pārivrājyaṃ śrūyate tataḥ katham ahiṃsādeḥ para-dharmatvam iti cet satyaṃ, pūrva-pūrvāśrama-dharmaiḥ kṣīṇa-vāsanayā pārivrājyādhikāre sati taṃ praty ahiṃsādeḥ sva-dharmatvena vihitatvāt | ataeva sva-dharme sthitasyeti yojyate