B.G 18.51-55

बुद्ध्या विशुद्धया युक्तो धृत्याऽऽत्मानं नियम्य च। शब्दादीन् विषयांस्त्यक्त्वा रागद्वेषौ व्युदस्य च ॥५१॥

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

[बुद्ध्या (buddhyā) - with intellect; विशुद्धया (viśuddhayā) - purified; युक्तः (yuktaḥ) - engaged; धृत्या (dhṛtyā) - with determination; आत्मानं (ātmānaṃ) - self; नियम्य (niyamya) - controlling; च (ca) - and; शब्दादीन् (śabdādīn) - sound, etc.; विषयान् (viṣayān) - senses; त्यक्त्वा (tyaktvā) - abandoning; रागद्वेषौ (rāgadveṣau) - attachment and aversion; व्युदस्य (vyudasya) - having discarded; च (ca) - and;]

विविक्तसेवी लघ्वाशी यतवाक्कायमानसः। ध्यानयोगपरो नित्यं वैराग्यं समुपाश्रितः ॥५२॥

viviktasevī laghvāśī yatavākkāyamānasaḥ। dhyānayogaparo nityaṃ vairāgyaṃ samupāśritaḥ ॥52॥

[विविक्तसेवी (viviktasevī) - one who enjoys solitude; लघ्वाशी (laghvāśī) - moderate eater; यतवाक्कायमानसः (yatavākkāyamānasaḥ) - controlled in speech, body, and mind; ध्यानयोगपरो (dhyānayogaparaḥ) - devoted to meditation and yoga; नित्यम् (nityam) - always; वैराग्यम् (vairāgyam) - dispassion; समुपाश्रितः (samupāśritaḥ) - having fully taken refuge;]

अहङ्कारं बलं दर्पं कामं क्रोधं परिग्रहम्। विमुच्य निर्ममः शान्तो ब्रह्मभूयाय कल्पते ॥५३॥

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

[अहङ्कारं (ahaṅkāram) - ego; बलं (balam) - strength; दर्पं (darpam) - pride; कामं (kāmam) - desire; क्रोधं (krodham) - anger; परिग्रहम् (parigraham) - possessiveness; विमुच्य (vimucya) - having abandoned; निर्ममः (nirmamaḥ) - without a sense of ownership; शान्तः (śāntaḥ) - peaceful; ब्रह्मभूयाय (brahmabhūyāya) - to state of abiding in Brahman; कल्पते (kalpate) - is fit.;]

ब्रह्मभूतः प्रसन्नात्मा न शोचति न काङ्क्षति। समः सर्वेषु भूतेषु मद्भक्तिं लभते पराम् ॥५४॥

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

[ब्रह्मभूतः (brahmabhūtaḥ) - one who is realized in Brahman; प्रसन्नात्मा (prasannātmā) - with a pleased mind; न (na) - does not; शोचति (śocati) - lament; न (na) - does not; काङ्क्षति (kāṅkṣati) - desire; समः (samaḥ) - equally disposed; सर्वेषु (sarveṣu) - to all; भूतेषु (bhūteṣu) - beings; मद्भक्तिं (madbhaktiṃ) - My devotion; लभते (labhate) - gains; पराम् (parām) - supreme;]

भक्त्या मामभिजानाति यावान् यश्चास्मि तत्त्वतः। ततो मां तत्त्वतो ज्ञात्वा विशते तदनन्तरम् ॥५५॥

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

[भक्त्या (bhaktyā) - by devotion; माम् (mām) - me; अभिजानाति (abhijānāti) - he knows; यावान् (yāvān) - how much; यः (yaḥ) - who; च (ca) - and; अस्मि (asmi) - I am; तत्त्वतः (tattvataḥ) - in reality; ततः (tataḥ) - then; माम् (mām) - me; तत्त्वतः (tattvataḥ) - in reality; ज्ञात्वा (jñātvā) - having known; विशते (viśate) - he enters; तत् (tat) - that; अनन्तरम् (anantaram) - afterwards;]

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.

ब्रह्मभूयाय कल्पते - ब्रह्मणि भावः ब्रह्मभूयम्। ब्रह्मणि स्थितिः सर्वदा तन्मनस्कतेत्यर्थः ॥५३॥

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

[ब्रह्मभूयाय (brahmabhūyāya) - to the state of Brahman; कल्पते (kalpate) - is considered; ब्रह्मणि (brahmaṇi) - in Brahman; भावः (bhāvaḥ) - state; ब्रह्मभूयम् (brahmabhūyam) - state of being Brahman; ब्रह्मणि (brahmaṇi) - in Brahman; स्थितिः (sthitiḥ) - abiding; सर्वदा (sarvadā) - always; तन्मनस्कता (tanmanaskatā) - mindfulness of that; इति (iti) - thus; अर्थः (arthaḥ) - meaning;]

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.