B.G 5.21

बाह्यस्पर्शेष्वसक्तात्मा विन्दत्यात्मनि यत् सुखम्। स ब्रह्मयोगयुक्तात्मा सुखमक्षयमश्नुते ॥२१॥

The one who is disinterested in the external engagement of sense organs, experiences within himself happiness. The person engaging in the practice of 'Brahma-Yoga' obtains the same happiness in everlasting proportion.

Gīta Bhāshya 5.21

The remaining part of this chapter explains the combined knowledge of renunciation and Yoga. Superiority of Yōga over mere renunciation is clarified by emphasizing the undiminishing happiness one gets through Brahma-Yōga .

सन्यास योग ज्ञानानि मिलित्वा प्रपञ्चयति अध्याय शेषेण।

The remaining part of this chapter explains the combined knowledge of renunciation and Yoga.

पुनः योगस्य आधिक्यं स्पष्टयति - बाह्यस्पर्शेषु इति।

Again, the superiority of Yōga (over mere renunciation) is clarified by 'bāhyasparśeṣu' verse.

कामरहितः आत्मनि यत् सुखं विन्दति स एव ब्रह्मयोगयुक्तात्मा चेत् तदेव अक्षयं सुखं विन्दति। ब्रह्मविषयो योगः ब्रह्मयोगः। ध्यानादियुक्तस्यैव आत्मसुखम् अक्षयम्। अन्यथा नेत्यर्थः ॥२१॥

The happiness experienced by one who is without desire, that same happiness in everlasting proportion without diminishing, is experienced by one who engages in 'Brahma Yōga'. Practice of Yōga on the topics concerning Brahman is 'Brahma Yōga'. By engaging in meditation (Dhyāna) alone, the happiness of self becomes everlasting and undiminishing. Otherwise not, is the meaning.

Gīta Tātparya 5.21

Remembering the Supreme Lord is the 'Brahma-Yōga' .

इदानीमपि परमात्मनि स्मृऽतमात्रे सुखं विन्दतीति यत् तदा स एव सम्यगुक्तः किमु ॥२१॥

When even little rememberance of the Supreme Lord indeed gives happiness, what then of those who undertake it well?