योऽन्तःसुखोऽन्तरारामस्तथान्तर्ज्योतिरेव यः ।
स योगी ब्रह्मनिर्वाणं ब्रह्मभूतोऽधिगच्छति ॥ २४ ॥ (5.24)
One who is happy within, whose pleasure is within, and who has his light only within, that yogi, who is at all times one with Brahman, attains Brahman which is final emancipation.
अन्त: सुख:, one who is happy within, one whose happiness is intrinsic to himself and independent, indeed, of external objects; How does the absense of external happiness occur? As to that Sri Krishna says अन्तराराम:, one whose pleasure is within–he is one whose आराम, disport, is in the indwelling Self alone, and not in such objects as women etc which are the means to external happiness.
That is, he is without the means of external happiness because of his being totally without possessions. (See 4.21)
Well, how can a sanyasi be devoid of the happiness and the means to it, since for him, even though totally without possession, there is the possibility of happiness arising from such unsought for sense-experiences as the hearing of a sweet music or the sound of a kuyil from somewhere, the touch of gentle breeze, the seeing of moonrise, the dance of a peacock etc., the drinking of a very sweet and cool water of the Cauvery, the smelling of the fragrance of jazmine flower and so on?
To that Sri Krishna says: तथा अन्तर्-ज्योतिरेव-य:, and who has his light only within: he is one whose ज्योतिः, light, Consciousness, is only within (अन्तर्) in the Self, and is not deried from the external organs, just as his happiness is only within and not derived from external objects; he is devoid of all objective knowledge, of sound etc., derived from the ear etc.
The word एव, only, is to be joined with all the adjectives.
Since during the period of समाधि there is no perception of sound etc., and since even though they are experienced during the state of व्युत्थान (awakening) there is still conviction of their unreality, therefore there is no possibility of any happiness arising to him from external objects. This is the idea.
स योगी, that yogi, who is endued with the qualifications as mentioned, who is merged in समाधि; अधिगच्छति, attains; ब्रह्मनिर्वाणं, Brahman which is final Emancipation.
Brahman is supreme Bliss, and That is itself is निर्वाण, final Emancipation, being by nature identical with the cessation of the duality which is imaginary.
For, the cessation of whatever is imagined on something is tantamount to nothing but the substratum remaining as it is.
He attains the ever-attained through the cessation of the veil of nescience, because at all times, indeed, he is ब्रह्मभूत:, one with Brahman and nothing else, as is said in the Sruti:
ब्रह्मैव सन्ब्रह्माप्येति, Being but Brahman he is merged in Brahman. (Brihadaranyaka Upanishad 4.4.6)
And in Brahmasutra it says अवस्थितेरिति काशकृत्स्नः (1.4.22).
Kaasakrtsna thinks that the statement about the identity is in order because of the existence of the supreme Self as the जीव.
लभन्ते ब्रह्मनिर्वाणमृषयः क्षीणकल्मषाः ।
छिन्नद्वैधा यतात्मानः सर्वभूतहिते रताः ॥ २५ ॥ (5.25)
Those whose sins have been attenuated ie. weakened in force or effect, who are Seers, who are freed from doubts, whose organs are well under control, who are engaged in doing good to all beings, attain Brahman which is final Emancipation.
Those who, through sacrifices etc., are first क्षीणकल्मषाः, have their sins attenuated; and then through purification of the mind have become र्षय: Seers, sanyasis, who are capable of podering on subtle things; and through the perfection of श्रवण etc., छिन्नद्वैधा:, freed from all doubts; then through the perfection of निदिध्यासन, यतात्मानः, have their organs fully under control, have their minds concentrated only on the supreme Self; and the persons of this kind who, on account of their not perceiving duality, are रताः, engaged; सर्वभूतहिते, in doing good to all beings, ie. who are without cruelty, who are knowers of Brahman; लभन्ते, attain; ब्रह्मनिर्वाणम्, Brahman which is final Emancipation, as it is said in the Sruti:
यस्मिन्सर्वाणि भूतानि आत्मैवाभूद्विजानतः । तत्र को मोहः कः शोक एकत्वमनुपश्यतः ॥ ७॥ (Isaavaasya Upanishad 7)
When to the man of realization all beings become the very Self, then what delusion and what sorrow can there be for that seer of Oneness?