Bhashya
स वै यः ‘आत्मापहतपाप्मा’ इति प्रकृतः, वै-शब्देन तं स्मारयति ।एषः विवक्षित आत्मा हृदि हृदयपुण्डरीके आकाशशब्देनाभिहितः ।तस्य एतस्य हृदयस्य एतदेव निरुक्तं निर्वचनम्, नान्यत् ।हृदि अयमात्मा वर्तत इति यस्मात्, तस्माद्धृदयम्, हृदयनामनिर्वचनप्रसिद्ध्यापि स्वहृदये आत्मेत्यवगन्तव्यमित्यभिप्रायः ।अहरहर्वा प्रत्यहम् एवंवित् हृदि अयमात्मेति जानन् स्वर्गं लोकं हार्दं ब्रह्म एति प्रतिपद्यते ।ननु अनेवंविदपि सुषुप्तकाले हार्दं ब्रह्म प्रतिपद्यते एव,‘सत्ता सोम्य तदा संपन्नः’ इत्युक्तत्वात् ।बाढमेवम्, तथाप्यस्ति विशेषः-- यथा जानन्नजानंश्च सर्वो जन्तुः सद्ब्रह्मैव, तथापि तत्त्वमसीति प्रतिबोधितः विद्वान्-सदेव नान्योऽस्मि- इति जानन् सदेव भवति; एवमेव विद्वा नविद्वांश्च सुषुप्ते यद्यपि सत्संपद्यते, तथाप्येवंविदेव स्वर्गं लोकमेतीत्युच्यते ।देहपातेऽपि विद्याफलस्यावश्यंभावित्वा दित्येष विशेषः ॥
In plain words
Scripture recalls to us that precise Self described as 'free from sin.' This intended Self is what the word 'space' points to within the lotus of the heart. The very name 'heart' derives from this truth: because the Self dwells here, it is called the heart. The one who knows this daily attains that heart-abiding Brahman, the luminous world. If someone objects that even the ignorant person reaches this heart-abiding Brahman during deep sleep—as scripture says, 'O gentle one, then he is united with pure Being'—we grant the premise, yet point out a vital difference. Just as every creature rests in pure Being during sleep whether they know it or not, the enlightened person who has been awakened by the teaching 'Thou art that' knows consciously 'I am pure Being itself' and remains established as Being. Both may reach Being in sleep, but only the conscious knower attains the luminous realm of liberation when the physical body falls away, because knowledge bears its unfailing fruit.
Close to the Sanskrit
That indeed who is spoken of as 'the Self free from sin', by the word 'vai' he reminds [us]. This intended Self is spoken of in the heart, the heart-lotus, by the word 'space'. Of this very heart this is the very etymological derivation, none other: because this Self abides in the heart, therefore 'heart'. Day by day indeed the knower thus, knowing that this Self is in the heart, attains the heavenly world, the heart-abiding Brahman. Now, does not even one who does not thus know attain the heart-abiding Brahman in deep sleep, since it is said 'O gentle one, then he is united with Existence'? Granted this; nevertheless there is a difference: just as every creature, whether knowing or not knowing, is Existence-Brahman indeed, yet the wise one, awakened by 'Thou art that', knowing 'I am Existence itself, no other', becomes Existence indeed; similarly, although both the wise and the ignorant attain Existence in deep sleep, yet it is said that only one who knows thus attains the heavenly world. Even at the fall of the body, because of the inevitability of the fruit of knowledge, this is the distinction.