BhG 6.27

syntax

uttamam (supreme) sukham (happiness) enam (to this) śānta-rajasam (whose rajas is pacified) praśānta-manasam (whose mind is pacified) akalmaṣam (sinless) brahma-bhūtam (being brahman) yoginam hi (indeed to a yogī) upaiti (it comes).

grammar

praśānta-manasam	–	praśānta-manas 1n.1 m.; BV: yasya manaḥ praśāntam asti tam – whose mind is pacified (from: pra-√śam – to calm, to put to an end, to destroy, PP praśānta – pacified, calm; √man – to think, manas – the mind);
hi	–	av. – because, just, indeed, surely;
enam	–	etat sn. 2n.1 m. – to this;
yoginam	–	yogin 2n.1 m. – a yogī, engaged (from: √yuj – to yoke, to join, to engage, yoga – yoga, yoking, application, a means, one of the schools of Hindu philosophy);
sukham	–	sukha 1n.1 n. – happiness, pleasure, comfort (from: su – prefix: good, excellent, beautiful, virtuous; kha – cavity, hole, nave; su-kha – joy, happiness, literally: good hole in the nave [of a wheel through which an axis runs] that makes the moving smooth; or from: su-√sthā; opposite to: duḥkha – pain, difficulty);
uttamam	–	uttama 1n.1 n. – uppermost, highest, most elevated (superlative of: ud – upwards, above);
upaiti	–	upa-√i (to go near, to attain) Praes. P 1v.1 – it comes;
śānta-rajasam	–	śānta-rajas 2n.1 m.; BV: yasya rajaḥ śāntam asti tam – whose rajas is pacified (from: √śam – to calm, to put to an end, to destroy, PP śānta – calm, tranquil; √rañj – to be dyed, be excited, be delighted, rajas – coloured, dust, passion);
brahma-bhūtam	–	brahma-bhūta 2n.1 m.; TP: brahmaṇi bhūtam iti – being in brahman / being brahman (from: √bṛh – to increase, brahman – spirit, the Vedas; √bhū – to be, PP bhūta – been, real, world);
akalmaṣam	–	a-kalmaṣa 2n.1 m. – spotless, sinless (from: karma+so – destroying good acts);

textual variants

yoginaṁ sukham uttamam → yoginaṁ sukham uttaram / yasmād yoginam uttamaṁ (higher happiness, to a yogī / from which to a yogī highest);
upaiti → abhyeti (it comes);
śānta-rajasaṁ → śāṁti-rajasaṁ / śāṁta-manasam (having pacified rajas / having pacified mind);

Śāṃkara

praśāntamanasaṃ prakarṣeṇa śāntaṃ mano yasya saḥ praśāntamanās taṃ praśāntamanasaṃ hi enaṃ yoginaṃ sukham uttamaṃ nitiśayam upaiti upagacchati śānta-rajasaṃ prakṣīṇa-mohādi-kleśa-rajasam ity arthaḥ, brahma-bhūtaṃ jīvanmuktaṃ brahmaiva sarvam ity evaṃ niścayavantaṃ brahma-bhūtam akalmaṣaṃ dharmādharmādi-varjitam

Rāmānuja

praśāntamanasam ātmani niścalamanasam, ātmanyastamanasaṃ tad eva hetor dagdhāśeṣakalmaṣam, tata eva śāntarajasaṃ vinaṣṭarajoguṇam, tata eva brahmabhūtaṃ svasvarūpeṇāvasthitam enaṃ yoginam ātmasvarūpānubhavarūpam uttamaṃ sukham upaiti / hīti hetau; uttamasukharūpatvād ātmasvarūpasyetyarthaḥ

Śrīdhara

evaṃ pratyāhārādibhiḥ punaḥ punar mano vaśīkurvan rajo-guṇa-kṣaye sati yoga-sukhaṃ prāpnotīty āha praśānteti | evam ukta-prakāreṇa śāntaṃ rajo yasya tam | ataeva praśāntaṃ mano yasya tam enaṃ niṣkalmaṣam brahmatvaṃ prāptaṃ yoginaṃ uttamam sukhaṃ samādhi-sukhaṃ svayam evopaiti prāpnoti

Madhusūdana

evaṃ yogābhyāsa-balād ātmany eva yoginaḥ praśāmyati manaḥ | tataś ca praśānteti | prakarṣeṇa śāntaṃ nirvṛttikatayā niruddhaṃ saṃskāra-mātra-śeṣaṃ mano yasya taṃ praśānta-manasaṃ vṛtti-śūnyatayā nirmanaskam | nirmanaskatve hetu-garbhaṃ viśeṣaṇa-dvayaṃ śānta-rajasaṃ akalmaṣam iti | śāntaṃ vikṣepakaṃ rajo yasya taṃ vikṣepa-śūnyam | tathā na vidyate kalmaṣam laya-hetus tamo yasya tam akalmaṣam laya-śūnyam | śānta-rajasam ity anenaiva tamo-guṇopalakṣaṇe ‚ kalmaṣam saṃsāra-hetu-dharmādharmādi-varjitam iti vā | brahma-bhūtaṃ brahmaiva sarvam iti niścayena samaṃ brahma prāptaṃ jīvan-muktam enaṃ yoginam | evam uktena prakāreṇeti śrīdharaḥ | uttamaṃ niratiśayaṃ sukham upaity upagacchati | manas tad-vṛttyor abhāve suṣuptau svarūpa-sukhāvirbhāva-prasiddhiṃ dyotayati hi-śabdaḥ | tathā ca prāg-vyākhyātaṃ sukham ātyantikaṃ yat tad ity atra

Viśvanātha

tataś ca pūrvavad eva tasya samādhisukhaṃ syād ity āha praśānteti | sukhaṃ kartṛ yoginam upaiti prāpnoti

Baladeva

evaṃ prayatamānasya pūrvavad eva samādhi-sukhaṃ syād ity āha praśānteti | praśāntam ātmany acalaṃ mano yasya tam | ataevākalmaṣaṃ dagdha-prāktana-sūkṣma-doṣam | ataeva śānta-rajasam | brahma-bhūtaṃ sākṣāt-kṛta-viviktāvirbhāvitāṣṭa-guṇakātma-svarūpaṃ yoginaṃ praty uttamam ātmānubhava-rūpaṃ mahat sukhaṃ kartā svayam evopaiti