BhG 18.30

syntax

he pārtha (O son of Pṛthā!),
yā [buddhiḥ] (which intelligence) pravṛttim ca nivṛttim ca (and activity and cessation) kāryākārye (what is to be done and what is not to be done) bhayābhaye (fear and fearlessness) bandham mokṣam ca (bondage and liberation) vetti (it knows),
sā buddhiḥ (that intelligence) sāttvikī [asti] (is sattvic).

grammar

pravṛttim	–	pravṛtti 2n.1 f. – activity (from: pra-√vṛt – to start to act, to surpass);
ca	–	av. – and;
nivṛttim	–	nivṛtti 2n.1 f. – cessation, stopping (from: ni-√vṛt – to stop, to turn back);
ca	–	av. – and;
kāryākārye	–	kārya-akārya 2n.2 n. – duty and improper act (from: √kṛ – to do, PF kārya – to be done, work, duty, especially religious one);
bhayābhaye	–	bhaya-abhaya 2n.2 n. – fear and fearlessness (from: √bhī – to scare, bhaya – fear);
bandham	–	bandha 2n.1 m. – fetters, bondage (from: √bandh – to bind, to fetter);
mokṣam	–	mokṣa 2n.1 m. – liberation, deliverance, casting away (from: √muc – to liberate);
ca	–	av. – and;
yā	–	yat sn. 1n.1 f. – which;
vetti	–	√vid (to know, to understand) Praes. P 1v.1 – it knows;
buddhiḥ	–	buddhi 1n.1 f. – intelligence, thought, understanding, knowledge, idea, opinion (from: √budh – to wake, to perceive, to understand);
sā	–	tat sn. 1n.1 f. – that;
pārtha	–	pārtha 8n.1 m. – O son of Pṛthā (from: √pṛth – to extend, pṛthā – Kuntī, mother of the sons of Pāṇḍu);
sāttvikī	–	sāttvikī 1n.1 f. – pertaining to sattva, sattvic (from: √as – to be, PPr sant – being, existing, true, the essence, abst. sattva – being, essence, wisdom, spirit, one of the three guṇas);

textual variants

kāryākārye → kāryākāryau (duty and improper activity);
yā → yo (that which);
vetti buddhiḥ sā pārtha sāttvikī → buddhir veda sā sātvikī matā (you must know that this intelligence is considered sattvic);

The first pada of verse 18.30 is the same as the first pada of verse BhG 16.7;

Śāṃkara

pravṛttiṃ ca pravṛttiḥ pravartanaṃ bandha-hetuḥ karma-mārgaḥ śāstra-vihita-viṣayaḥ | nivṛttiṃ ca nirvṛttir mokṣa-hetuḥ saṃnyāsa-mārgaḥ | bandha-mokṣa-samāna-vākyatvāt pravṛtti-nivṛttī karma-saṃnyāsa-mārgāv ity avagamyate | kāryākārye vihita-pratiṣiddhe laukike vaidike vā śāstra-buddheḥ kartavyākartavye karaṇākaraṇe ity etat | kasya ? deśa-kālādy-apekṣayā dṛṣṭādṛṣṭārthānāṃ karmaṇām | bhayābhaye bibhety asmād iti bhayaṃ cora-vyāghrādi, na bhayam abhayam, bhayaṃ cābhayaṃ ca bhayābhaye, dṛṣṭādṛṣṭa-viṣayayor bhayābhayayoḥ kāraṇe ity arthaḥ | bandhaṃ sa-hetukaṃ mokṣaṃ ca sa-hetukaṃ yā vetti vijānāti buddhiḥ, sā pārtha sāttvikī | tatra jñānaṃ buddher vṛttir buddhis tu vṛttimatī | dhṛtir api vṛtti-viśeṣa eva buddheḥ

Rāmānuja

pravṛttiḥ abhyudayasādhanabhūto dharmaḥ, nivṛttiḥ mokṣasādhanabhūtaḥ, tav ubhau yathāvasthitau yā buddhir vetti; kāryākārye sarvavarṇānāṃ pravṛttinivṛttidharmayor anyataraniṣṭhānāṃ deśakālāvasthāviśeṣeṣu „idaṃ kāryam, idam akāryam” iti yā vetti; bhayābhaye śāstrātivṛttir bhayasthānaṃ tadanuvṛttir abhayasthānam, bandhaṃ mokṣaṃ ca saṃsārayāthātmyaṃ tadvigamayāthātmyaṃ ca yā vetti; sā sāttvikī buddhiḥ

Śrīdhara

atra buddhes traividhyam āha pravṛttiṃ ceti tribhiḥ | pravṛttiṃ dharme | nivṛttim adharme | yasmin deśe kāle ca yat kāryam akāryaṃ ca | bhayābhaye kāryākārya-nimittau arthānarthau | kathaṃ bandhaḥ kathaṃ vā mokṣe iti yā buddhir antaṃkaraṇaṃ vetti sā sāttvikī | yayā pumān vettīti vaktavye karaṇe kartṛtvopacāraḥ kāṣṭhāni pacantītivat

Viśvanātha

bhayābhaye saṃsārāsaṃsāra-hetuke

Baladeva

tatra buddhes traividhyam āha pravṛttiṃ ceti tribhiḥ | yā buddhir dharme pravṛttim adharmān nivṛttiṃ ca vetti, yayā vettīti vaktavya yā vettīti karaṇe kartṛtvam upacaritam | kuṭhāraś chinattītivat | niṣkāmaṃ karma kāryaṃ sa-kāmaṃ tv akāryam iti kāryākārye yā vetti aśāstrīya-pravṛttito bhayaṃ śāstrīya-pravṛttitas tv abhayam iti bhayābhaye yā vetti, bandhaṃ saṃsāra-yāthātmyaṃ mokṣaṃ tac-cheda-yāthāmyaṃ ca yā vetti sā buddhiḥ sāttvikī