BhG 2.54

syntax

arjuna (Arjuna) uvāca (he spoke):
he keśava (O Keśava!),
sthita-prajñasya (of one who has firm wisdom) samādhi-sthasya (of one situated in concentration) kā bhāṣā (what is the description?).
sthita-dhīḥ (one who has a steady thought) kim prabhāṣeta (how he would speak?),
kim āsīta (how he would sit?),
kim vrajeta (how he would walk?).

grammar

arjunaḥ	–	arjuna 1n.1 m. – white, clear, Arjuna;
uvāca	–	√vac (to speak) Perf. P 1v.1 – he spoke;
sthita-prajñasya	–	sthita-prajña 6n.1 m.; BV: yasya prajñā sthitāsti tasya – of one whose wisdom is firm (from: √sthā – to stand, PP sthita – standing, situated, firm; pra-√jñā – to know, to understand, to discern, prajñā – discrimination, wisdom, judgement);
kā	–	kim sn. 1n.1 f. – what?
bhāṣā	–	bhāṣā 1n.1 f. – spech, language, description, definition (from: √bhāṣ – to speak);
samādhi-sthasya	–	samādhi-stha 6n.1 m. – yaḥ samādhau tiṣṭhati tasya – of one situated in concentration (from: sam-ā-√dhā – to put, to fix, to compose, to concentrate, samādhi – union, concentration, harmony; √sthā – to stand, stha – suffix: being in);
keśava	–	keśa-va 8n.1 m. – who has [beautiful] hair (from: keśa – hair; -va = -vant – owner); or ka-īśa-va – the lord of Brahmā and Śiva(from: ka – Brahmā; √xīś – to own, to reign, īśa – ruler, lord, Śiva; -va = -vant – owner);
sthita-dhīḥ	–	sthita-dhī 1n.1 m.; BV: yasya dhīḥ sthitāsti saḥ – who has a steady thought (from: √sthā – to stand, PP sthita – standing, situated, firm; √dhī – to think, to reflect, dhī – thought, intelligence);
kim	–	av. – whether? how? why? wherefrom? (from: kim – what?);
prabhāṣeta	–	pra-√bhāṣ (to speak) Pot. Ā 1v.1 – he would speak;
kim	–	av. – whether? how? why? wherefrom? (from: kim – what?);
āsīta	–	√ās (to sit, to exist) Pot. Ā 1v.1 – he would sit;
vrajeta	–	√vraj (to go, to walk) Pot. Ā 1v.1 – he would walk;
kim	–	av. – whether? how? why? wherefrom? (from: kim – what?);

textual variants

sthita-prajñasya → sthira-prajñasya (of one whose wisdom is fixed);
sthitadhīḥ → sthiradhīḥ (who has a fixed thought);
prabhāṣeta → vibhāṣeta (he would speak);
vrajeta → vrajec ca (and he would walk);
kim āsīta vrajeta kim → samāseta vrajeta kāṁ (he would sit together, he would walk, what);

Śāṃkara

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

The characteristic attributes of a perfect Sage. Having found an occasion for interrogation, Arjuna asks with a desire to know the characteristic marks of one who has attained wisdom in steady contemplation (samādhi-prajña):		praśna-bījaṃ pratilabhya arjuna uvāca labdha-samādhi-prajñasya lakṣaṇa-bubhutsayā –
Arjuna said: What, O Keśava! , is the description of one of steady knowledge, who is constant in con temptation? How does one of steady knowledge speak, how sit, how move?		arjuna uvāca sthita-prajñasya kā bhāṣā samādhi-sthasya keśava | sthita-dhīḥ kiṃ prabhāṣeta kim āsīta vrajeta kim ||2.54||
How is a man who has a firm conviction that he is the Supreme Brahman, and who is intent on contemplation (samadhi), – how is such a man spoken of by others? How does the man of steady knowledge himself speak?		sthitā pratiṣṭhitā aham asmi paraṃ brahma iti prajñā yasya saḥ sthita-prajñas tasya sthita-prajñasya kā bhāṣā kiṃ bhāṣaṇaṃ vacanaṃ katham asau parair bhāṣyate samādhi-sthasya samādhau sthitasya he keśava |
How does he sit? How does he move? –		sthita-dhīḥ sthita-prajñaḥ svayaṃ vā kiṃ prabhāṣeta | kim āsīta vrajeta kim āsanaṃ vrajanaṃ vā tasya katham ity arthaḥ |
In this verse Arjuna asks in order to know what the characteristic attributes of a man of steady knowledge (sthitaprajña) are.		sthita-prajñasya lakṣaṇam anena ślokena pṛcchati[1] ||2.54||
		[1] pṛcchayate

Rāmānuja

evam uktaḥ pārtho niḥsaṅga-karmānuṣṭhāna-rūpa-karma-yoga-sādhya-sthita-prajñatayā yoga-sādhana-bhūtāyāḥ svarūpaṃ sthita-prajñasyānuṣṭhāna-prakāraṃ ca pṛcchati—samādhi-sthasya sthita-prajñasya kā bhāṣā ko vācakaḥ śabdaḥ ? tasya svarūpaṃ kīdṛśam ity arthaḥ | sthita-prajñaḥ kiṃ ca bhāṣaṇādikaṃ karoti

Śrīdhara

pūrva-ślokoktasyātma-tattva-jñasya lakṣaṇaṃ jijñāsur arjuna uvāca – sthita-prajñasyeti | svābhāvike samādhau sthitasya, ataeva sthitā niścalā prajñā buddhir yasya tasya bhāṣā kā ? bhāṣyate ‚nayā iti bhāṣā lakṣaṇam iti yāvat | sa kena lakṣaṇena sthita-prajña ucyate ity arthaḥ | tathā sthita-dhīḥ kiṃ kathaṃ bhāṣaṇam āsanaṃ vrajanaṃ ca kuryād ity arthaḥ

Madhusūdana

evam labdhāvasaraḥ sthita-prajña-lakṣaṇaṃ jñātum arjuna uvāca | yāny eva hi jīvan-muktānāṃ lakṣaṇāni tāny eva mumukṣūṇāṃ mokṣopāya-bhūtānīti manvānaḥ | sthitā niścalā ahaṃ-brahmāsmi iti prajñā yasya sa sthita-prajño ‚vasthā-dvayavān samādhistho vyutthita-cittaś ceti | ato viśinaṣṭi samādhi-sthasya sthita-prajñasya kā bhāṣā ? karmaṇi ṣaṣṭhī | bhāṣyate ‚nayeti bhāṣā lakṣaṇam | samādhi-sthaḥ sthita-prajñaḥ kena lakṣaṇenānyair vyavahriyata ity arthaḥ |
sa ca vyutthita-cittaḥ sthita-dhīḥ sthita-prajñaḥ svayaṃ kiṃ prabhāṣeta ? stuti-nindādāv abhinandana-dveṣādi-lakṣaṇaṃ kiṃ kathaṃ prabhāṣeta ? sarvatra sambhāvanāyāṃ liṅ | tathā kim āsīteti vyutthita-citta-nigrahāya kathaṃ bahir indriyāṇāṃ nigrahaṃ karoti ? tan-nigrāhābhāva-kāle kiṃ vrajeta kathaṃ viṣayān prāpnoti ? tat-kartṛka-bhāṣaṇāsana-vrajanāni mūḍha-jana-vilakṣaṇāni kīdṛśānīity arthaḥ |
tad evaṃ catvāraḥ praśnāḥ samādhi-sthe sthita-prajña ekaḥ | vyutthite sthita-prajñe traya iti | keśaveti sambodhayan sarvāntaryāmitayā tvam evaitādṛśaṃ rahasyaṃ vaktuṃ samartho ‚sīti sūcayati

Viśvanātha

samādhāv acalā buddhir iti śrutvā tattvato yogino lakṣaṇaṃ pṛcchati sthita-prajñasyeti | sthitā sthirācalā prajña buddhir yasyeti | kā bhāṣā ? bhāṣyate ‚nayeti bhāṣā lakṣaṇaṃ kiṃ lakṣaṇam ity arthaḥ | kīdṛśasya samādhi-sthasyeti samādhau sthāsyatīti | asyārthaḥ – evaṃ ca sthita-prajña iti | samādhi-stha iti jīvan-muktasya saṃjñā-dvayam | kiṃ prabhāṣeteti sukha-duḥkhayor mānāpamānayoḥ stuti-nindayoḥ sneha-dveṣayor vā samupasthitayoḥ kiṃ prabhāṣeta ? spaṣṭaṃ svagataṃ vā kiṃ vaded ity arthaḥ | kim āsīta ? tad indriyāṇāṃ bāhya-viṣayeṣu calanābhāvaḥ kīdṛśaḥ ? vrajeta kim ? teṣu calanaṃ vā kīdṛśam iti

Baladeva

evam ukto ‚rjunaḥ pūrva-padyoktasya sthita-prajñasya lakṣaṇaṃ jñātuṃ pṛcchati sthiteti | sthita-prajñe ‚tra catvāraḥ praśnāḥ – samādhisthe ekaḥ, vyutthite tu trayaḥ | tathā hi – sthitā sthirā prajña dhīr yasya tasya samādhi-sthasya kā bhāṣā kiṃ lakṣaṇam ? bhāṣyate ‚nayeti vyutpatteḥ | kena lakṣaṇena sthita-prajño ‚bhidhīyata ity arthaḥ | tathā vyutthitaḥ sthita-prajñaḥ kathaṃ bhāṣaṇādīni kuryāt ? tadīyāni tāni pṛthag-jana-vilakṣaṇāni kīdṛśānīty arthaḥ | tatra kiṃ prabhāṣeta ? svayoḥ stuti-nindayoḥ sneha-dveṣayoś ca prāptayor mukhataḥ svagataṃ vā kiṃ brūyāt ? kim āsīta bāhya-viṣayeṣu katham indriyāṇāṃ nigrahaṃ kuryāt ? vrajeta kim ? kiṃ tan-nigrāhābhāve ca kathaṃ viṣayānavāpnuyād ity arthaḥ | triṣu sambhāvanāyām