BhG 3.24

syntax

aham (I) cet (if) karma (work) na kuryām (I would not do),
[tarhi] (then) ime lokāḥ (these worlds) utsīdeyuḥ (they would decline),
[aham] ca (and I) saṅkarasya (of confusion) kartā (the cause) syām (I would be),
[tathā aham] (thus I) imāḥ (these) prajāḥ (creatures) upahanyām (I would harm).

grammar

utsīdeyuḥ	–	ut-√sad (to destroy, to decline) Pot. P 1v.3 – they would decline;
ime	–	idam sn. 1n.3 m. – these;
lokāḥ	–	loka 1n.3 m. – worlds;
na	–	av. – not;
kuryām	–	√kṛ (to do) Pot. P 3v.1 – I would do;
karma	–	karman 2n.1 n. – activity (from: √kṛ – to do);
cet	–	av. – if;
aham	–	asmat sn. 1n.1 – I;
saṁkarasya	–	saṁkara 6n.1 m. – of confusion [of social classes] (from: sam-√kṝ – to mix);
ca	–	av. – and;
kartā	–	kartṛ 1n.1 m. – the doer, the cause (from: √kṛ – to do);
syām	–	√as (to be) Pot. P 3v.1 – I would be;
upahanyām	–	upa-√han (to strike, to beat, to afflict) Pot. P 3v.1 – I would harm;
imāḥ	–	idam sn. 2n.3 f. – these;
prajāḥ	–	prajā 2n.3 f. – offspring, creatures, mankind (from: pra-√jan – to be born, be produced, to bring forth);

textual variants

ime → amī (those);
ced aham → ced iha (if here);
ca → tu (but);
upahanyām → apahanyām (I would destroy);

Śāṃkara

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

And what harm is there in that? – The Lord says:		tathā ca ko doṣa ity āha
These worlds would be ruined if I should not perform action; I should be the cause of confusion of castes, and should destroy these creatures.		utsīdeyur ime lokā na kuryāṃ karma ced aham | saṃkarasya ca kartā syām upahanyām imāḥ prajāḥ ||3.24||
If I should not perform action, then there would be no action conducive to the continuance of the universe, and all these worlds would fall into ruin.		utsīdeyur vinaśyeyur ime sarve lokāḥ loka-sthiti-nimittasya karmaṇo ’bhāvāt na kuryāṃ karma ced aham |
Moreover, I would be the author of confusion of castes, and thereby destroy these creatures. Thus, though working for the welfare of the creatures, I would bring about their ruin, – which would be unbecoming of Me, their lord.		kiṃ ca, saṃkarasya ca kartā syām | tena kāraṇena upahanyām imāḥ prajāḥ | prajānām anugrahāya pravṛtta tad-upahatim upahananaṃ kuryām ity arthaḥ | mama īśvarasyānanurūpam āpadyate ||3.24||

Rāmānuja

ahaṃ sarveśvaraḥ satyasaṅkalpaḥ svasaṅkalpakṛtajagadudayavibhavalayalīlaḥ chandato jagadupakṛtimartyo jāto ‚pi manuṣyeṣu śiṣṭajanāgresaravasudevagṛhe ‚vatīrṇas tatkulocite karmaṇy atandritas sarvadā yadi na varteya, mama śiṣṭajanāgresaravasudevasūnor vartma akṛtsnavidaḥ śiṣṭāḥ sarvaprakāreṇāyam eva dharma ity anuvartante; te ca svakartavyānanuṣṭhānena akaraṇe pratyavāyena ca ātmānam alabdhvā nirayagāmino bhaveyuḥ / ahaṃ kulocitaṃ karma na cet kuryām, evam eva sarve śiṣṭalokā madācarāyattadharmaniścayāḥ akaraṇād evotsīdeyuḥ naṣṭā bhaveyuḥ / śāstrīyācārānanupālanāt sarveṣāṃ śiṣṭakulānāṃ saṃkarasya ca kartā syām / ata evemāḥ prajāḥ upahanyām / evam eva tvam api śiṣṭajanāgresarapāṇḍutanayo yudhiṣṭhirānujo ‚rjunas san yadi jñānaniṣṭhāyām adhikaroṣi; tatas tvadācārānuvartino ‚kṛtsnavidaḥ śiṣṭā mumukṣavaḥ svādhikāram ajānantaḥ karmaniṣṭhāyāṃ nādhikurvanto vinaśyeyuḥ / ato vyapadeśyena viduṣā karmaiva kartavyam

Śrīdhara

tataḥ kiṃ ? ata āha utsīdeyur iti | utsīdeyur dharma-lopena naśyeyuḥ | tataś ca yo varṇa-saṅkaro bhavet tasyāpy aham eva kartā syāṃ bhaveyam | evam aham eva prajā upahanyāṃ malinīkuryām iti

Madhusūdana

śreṣṭhasya tava mārgānuvartitvaṃ manuṣyāṇām ucitam eva anuvartitve ko doṣa ity ata āha utsīdeyur iti | aham īśvaraś ced yadi karma na kuryāṃ tadā mad-anuvartināṃ manv-ādīnām api karmānupapatter loka-sthiti-hetoḥ karmaṇo lopeneme sarve lokā utsīdeyur vinaśyeyuḥ | tataś ca varṇa-saṃkarasya ca kartāham eva syām | tena cemāḥ sarvāḥ prajā aham evopahanyāṃ dharma-lopena vināśayeyam | kathaṃ ca prajānām anugrahārthaṃ pravṛtta īśvaro ‚haṃ tāḥ sarvā vināśayeyam ity abhiprāyaḥ |

yad yad ācaratīty āder aparā yojanā | na kevalaṃ loka-saṃgrahaṃ sampaśyan kartum arhasy api tu śreṣṭhācāratvād apīty āha yad yad iti | tathā ca mama śreṣṭhasya yādṛśa eva ācāras tādṛśa eva mad-anuvartinā tvayānuṣṭheyo na svātantryeṇānya ity arthaḥ | kīdṛśas tavācāro yo mayānuvartanīya ity ākāṅkṣāyāṃ na me pārthety ādibhis tribhiḥ ślokais tat-pradarśanam iti

Viśvanātha

utsīdeyur māṃ dṛṣṭāntīkṛtya dharmam akurvāṇā bhraṃśeyuḥ | tataś ca varṇa-saṅkaro bhavet tasyāpy aham eva kartā syām evam aham eva prajā hanyām | malināḥ kuryām

Baladeva

tataḥ kiṃ syād ity āha utsīdeyur iti | ahaṃ sarva-śreṣṭhaś cet śāstroktaṃ karma na kuryāṃ tarhīme lokā utsīdeyur vibhraṣṭa-maryādāḥ syuḥ | tad-vibhraṃśe sati yaḥ saṅkaraḥ syāt tasyāpy aham eva kartā syām | evaṃ ca prajāpatir aham imāḥ prajāḥ sāṅkarya-doṣeṇopahanyāṃ malināḥ kuryām | tathā ca – eṣa setur vidharaṇa eṣāṃ lokānām asaṃbhedāya iti śrutyā loka-maryādā-vidhārakatvena parigītasya me tan-maryādā-bhedakatvaṃ syād iti | evaṃ upadiśato ‚pi harer yat kiṃcit sva-bhakta-sukhecchoḥ svairācaritaṃ dṛṣṭaṃ, tat khalu vidhāyakena tad-vacasānupetatvād īśvarīyatvāc cāvarair naivācaraṇīyam | yad uktaṃ śrīmatā śukena –

īśvarāṇāṃ vacaḥ satyaṃ
tathaivācaritaṃ kvacit |
teṣāṃ yat sva-vaco-yuktaṃ
buddhimāṃs tat samācaret ||

naitat samācarej jātu
manasāpi hy anīśvaraḥ |
vinaśyaty ācaran mauḍhyād
yathārudro |bdhi-jaṃ viṣam || [BhP 10.33.31-2] iti