BhG 4.16

syntax

kim (what?) karma (activity) [asti] (it is),
kim (what?) akarma (inactivity) [asti] iti (it is)
atra (in this matter) kavayaḥ api (even the seers) mohitāḥ (bewildered) [santi] (they are).
yat (that which) jñātvā (after knowing)
aśubhāt (from misfortune) mokṣyase (you will be liberated),
tat (that) karma (activity) te (to you) pravakṣyāmi (I will declare).

grammar

kim	–	kim sn. 1n.1 n. – what?
karma	–	karman 1n.1 n. – activity (from: √kṛ – to do);
kim	–	kim sn. 1n.1 n. – what?
akarma	–	a-karman 1n.1 n. – inactivity (from: √kṛ – to do);
iti	–	av. – thus (used to close the quotation);
kavayaḥ	–	kavi 1n.3 m. – poets, bards, seers (from: √kav – to describe, to paint);
api	–	av. – although, moreover, besides, even;
atra	–	av. – here, in this matter;
mohitāḥ	–	mohita (√muh – to become confused, bewildered, stupefied) PP caus. 1n.3 m. – who are made bewildered;
tat	–	tat sn. 2n.1 n. – that;
te	–	yuṣmat sn. 4n.1 – to you (shortened form of: tubhyam);
karma	–	karman 2n.1 n. – activity (from: √kṛ – to do);
pravakṣyāmi	–	pra-√vac (to declare, to speak) Fut. P 3v.1 – I will declare;
yat	–	yat sn. 2n.1 n. – that which (correlative of: tat);
jñātvā	–	√jñā (to know, to understand) absol. – after understanding;
mokṣyase	–	√muc (to liberate) Fut. pass 2v.1 – you will be liberated;
aśubhāt	–	aśubha 5n.1 n. – from misfortune (from: √śubh – to shine, śubha – splendid, pleasant, auspicious, good);

textual variants

pravakṣyāmi → pravakṣāmi;
mokṣyase → mokṣase;
aśubhāt → śramāt (from weariness);

The fourth pada of verse 4.16 is the same as the fourth pada of verse BhG 9.1;

Śāṃkara

tatra karma cet kartavyaṃ tvad-vacanād eva karomy aham | kiṃ viśeṣitena ? pūrvaiḥ pūrvataraṃ kṛtaṃ [gītā 4.15] iti | ucyate —yasmān mahad vaiṣamyaṃ karmaṇi | kathaṃ ?

kiṃ karma kiṃ cākarmeti kavayo medhāvino’py atrāsmin karmādi-viṣaye mohitā mohaṃ gatāḥ | atas te tubhyam ahaṃ karmākarma ca pravakṣyāmi yaj jñātvā viditvā karmādi mokṣyase’śubhāt saṃsārāt

Rāmānuja

vakṣyamāṇasya karmaṇo durjñānatām āha

mumukṣuṇānuṣṭheyaṃ karma kiṃrūpam, akarma ca kim / akarmeti kartur ātmano yāthātmyajñānam ucyate; anuṣṭheyaṃ karma tadantargataṃ jñānaṃ ca kiṃrūpam ity ubhayatra kavayaḥ vidvāṃso ‚pi mohitāḥ yathāvan na jānanti / evam antargatajñānaṃ yat karma, tat te pravakṣyāmi, yaj jñātvānuṣṭhāya aśubhāt saṃsārabandhān mokṣyase / kartavyakarmajñānaṃ hy anuṣṭhānaphalam

Śrīdhara

tac ca tattvavidbhiḥ saha vicārya kartavyam | na loka-paramparā-mātreṇety āha kiṃ karmeti | kiṃ karma ? kīdṛśaṃ karma-karaṇam | kim akarma ? kīdṛśaṃ karmākaraṇam | ity asminn arthe vivekino ‚pi mohitāḥ | ato yaj jñātā yad-anuṣṭhāyāśubhāt saṃsārān mokṣyase mukto bhaviṣyasi tat karmākarma ca tubhyam ahaṃ pravakṣyāmi tac chṛṇu

Madhusūdana

nanu karma-viṣaye kiṃ kaścit saṃśayo ‚py asti yena pūrvaiḥ pūrvataraṃ kṛtam ity atinirbadhnāsi ? asty evety āha kiṃ karmeti | nau-sthasya niṣkriyeṣv api taṭastha-vṛkṣeṣu gamana-bhrama-darśanāt tathā dūrāc cakṣuḥ-saṃnikṛṣṭeṣu gacchatsv api puruṣeṣv agamana-bhrama-darśanāt paramārthataḥ kiṃ karma kiṃ vā paramārthato ‚karmeti kavayo medhāvino ‚py atrāsmin viṣaye mohitā mohaṃ nirṇayāsāmarthyaṃ prāptā atyanta-durnirūpatvād ity arthaḥ | tat tasmāt te tubhyam ahaṃ karma, a-kāra-praśleṣeṇa cchedād akarma ca pravakṣyāmi prakarṣeṇa sandehocchedena vakṣyāmi | yat karmākarma-svarūpaṃ jñātvā mokṣyase mukto bhaviṣyasy aśubhāt saṃsārāt

Viśvanātha

kiṃ ca karmāpi na gatānugatika-nyāyenaiva kevalaṃ vivekinā kartavyam | kintu tasya prakāra-viśeṣaṃ jñātvaivety atas tasya prathamaṃ durjñeyatvam āha

Baladeva

nanu kiṃ karma-viṣayakaḥ kaścit sandeho ‚py asti yataḥ pūrvaiḥ pūrvataraṃ kṛtam ity atinirbandhād bravīṣīti ced asty evety āha kiṃ karmeti | mumukṣubhir anuṣṭheyaṃ karma kiṃ rūpaṃ syād akarma ca karmānyat tad-antargataṃ jñānaṃ ca kiṃ rūpam ity arthaḥ | tad-anyatve enaṃ ca | atrārthe kavayo dhīmanto ‚pi mohitās tad-yāthātmya-nirṇayāsāmarthyān mohaṃ prāpuḥ | ahaṃ sarveśaḥ sarvajñas te tubhyaṃ tat karma a-kāra-praśleṣād akarma ca pravakṣyāmi yaj jñātvānuṣṭhāya prāpya cāśubhāt saṃsārān mokṣyase