B.G 18.51-55

buddhyā viśuddhayā yukto dhṛtyā''tmānaṃ niyamya ca। śabdādīn viṣayāṃstyaktvā rāgadveṣau vyudasya ca ॥51॥

viviktasevī laghvāśī yatavākkāyamānasaḥ। dhyānayogaparo nityaṃ vairāgyaṃ samupāśritaḥ ॥52॥

ahaṅkāraṁ balaṁ darpaṁ kāmaṁ krodhaṁ parigraham। vimucya nirmamaḥ śānto brahmabhūyāya kalpate ॥53॥

brahmabhūtaḥ prasannātmā na śocati na kāṅkṣati। samaḥ sarveṣu bhūteṣu madbhaktiṃ labhate parām ॥54॥

bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ। tato māṁ tattvato jñātvā viśate tad-anantaram ॥55॥

With intellect purified, engaged with determination, controlling oneself, and abandoning sensory objects like sound, one discards attachment and aversion; one who enjoys solitude, is a moderate eater, controlled in speech, body, and mind, is always devoted to meditation and yoga, and has fully embraced dispassion; having abandoned ego, strength, pride, desire, anger, and possessiveness, and who is free from the sense of ownership and is peaceful, is eligible to attain the state of abiding in Brahman. A person who is realized in Brahman, with a pleased mind, neither laments nor desires anything. Being equally disposed to all beings, such a person attains My supreme devotion. Through devotion, he knows me, how much and who I am in reality. Then, having known me in reality, he enters that afterwards.

Gīta Bhāshya 18.51-55

'brahmabhūyāya' - being in a constant state of mindfulness and abiding in Brahman.

brahmabhūyāya kalpate - brahmaṇi bhāvaḥ brahmabhūyam। brahmaṇi sthitiḥ। sarvadā tanmanaskatetyarthaḥ ॥53॥

In the term 'brahmabhūyāya kalpate', 'brahmabhūyāya' means the state of being in Brahman; it means being in a constant state of mindfulness and abiding in Brahman.

Gīta Tātparya 18.51-55

Having conducted oneself by the method being explained, thereafter, having perfected the art of performing actions that leave no-imprints, having reached the state of being in tune with Brahman, in the presence of goddess Mahalakshmi, i.e. Cit-Prakrti, how one attains liberation is explained.
'vimucya nirmamaḥ śāntaḥ' i.e. "Having become free, without attachment, peaceful" - means having attained 'naiṣkarmyasiddhiṁ', i.e. 'the perfecting the art of performing actions that does not leave imprints', one becomes 'brahmabhūyam' i.e. 'brahmaṇi bhūyāya' i.e. 'capable of residing in Brahman'.

vakṣyamāṇaprakāreṇa vartamānaḥ tadanantaraṃ naiṣkarmya sididhaṃ prāpto bhūtvā brahmākhyāyāḥ mahālakṣmyāḥ sakāśaṃ yathā prāpnoti tathā nibodha।

Having conducted oneself by the method being explained, thereafter, having obtained the perfection of performing actions that leave no-imprints, having reached the state of being in tune with Brahman, in the presence of goddess Mahalakshmi, i.e. Cit-Prakrti, how one attains liberation is explained.

mama yoniḥ rmahad brahma" "brahmaṇo hi pratiṣṭhāham" ityuktatvāt "brahmabhūtaḥ prasannātmā" ityuktvā "madbhaktiṃ labhate parām" iti vakṣyamāṇatvācca।

"My womb is the 'mahat', i.e. Cit-Prakrti", "Indeed, I am the foundation of Universe" - having said this, it is also said "One who has become in tune with Brahman, with a serene mind", "attains supreme devotion to me."

"sarvapāpakṣayād dehaṃ tyaktvā devān kramād vrajan। prāpya lakṣmīṃ tatprasādāt punaḥ svṛddhā harau yadā। bhaktistayā punarjñāne svṛddhe viṣṇuṃ prapadyate। aparokṣadṛśo viṣṇoḥ śarīre'pi sataḥ purā॥ tyaktadehādikasyāpi yāvadviṣṇuṃ prapadyate। tāvadguṇā vivardhante sthitāḥ syuḥ prāpya keśavam॥"

"After destroying all sins and leaving the body, one gradually ascends to the gods. By the grace of Lakshmi, one becomes prosperous in Hari. With further accumulation of devotion and knowledge, one surrenders to Vishnu. Even in the body one was formerly in existence, one obtains a direct vision of Vishnu. Even for one who has abandoned the body and others, until he surrenders to Lord Viṣṇu, his qualities increase and remain until he attains Lord Keśava."

iti mahāvarāhe॥

- stated thus in the great Varāha Purana.

"vimucya nirmamaḥ śāntaḥ" naiṣkarmyasiddhiṃ prāpto bhūtvā brahmaṇi bhūyāya bhavatītyarthaḥ॥

"vimucya nirmamaḥ śāntaḥ" i.e. "Having become free, without attachment, peaceful" - means having attained 'naiṣkarmyasiddhiṁ', i.e. perfecting the art of performing actions that does not leave imprints, one becomes 'brahmabhūyam' i.e. 'brahmaṇi bhūyāya' i.e. 'capable of residing in Brahman'.