Bhashya
अत्र किल षट्प्रश्नाः प्रश्नचतुष्टयं निरपेक्ष्येण अङ्गपूर्वत्वा-ङ्गफलम् , तस्मादिदं साङ्गं साम जानीयात्, यो जानीते सोऽमृतत्वं च गच्छतीत्युक्तार्थम् ।सावित्रादिमन्त्राणां हृदयाद्यङ्गस्थाने प्राप्तानाम् अत्र आदावेव अङ्गत्वविधानार्थमपकर्षस्तु उपक्रमोपसंहाराभ्यां विद्यैक्ये तात्पर्यं दर्शयति ।सावित्रीं प्रणवं यजुर्लक्ष्मीं स्त्रीशूद्राय स्त्री च शूद्रश्च स्त्रीशूद्रम् तस्मै स्त्रीशूद्राय नेच्छन्तीति निषेधं कुर्वन् प्रधानोपासनायां स्त्रीशूद्रस्याप्यधिकारं दर्शयति ।द्वात्रिंशदक्षरं साम जानीयादिति द्वात्रिंशदक्षराणां सामसंबंधं विधत्ते ।यो जानीते इत्याद्युक्तार्थम् ।सावित्रीं लक्ष्मीं यजुः प्रणवं यदि जानीयात् स्त्रीशूद्रः, स मृतः अधः नरकं गच्छतीति प्रत्यवायदर्शनेन निषेधमेव द्रढयति ।तस्मात्सर्वदा न आचष्टे इति कदाचिदपि न आचष्टे इत्याचार्यस्य निषेधं दर्शयति ।यद्याचष्टे स आचार्यः, तेनैव कथनेन मृतः अधः गच्छतीति प्रत्यवायदर्शनेन निषेधमेव द्रढयतीति ॥
In plain words
So there are, in fact, six questions here. The first four, taken as one block, already told us two things at once: that the limbs come first in order, and what fruit belongs to each -- that was the whole point of 'know this chant with its limbs; whoever knows it reaches immortality.' Now, the Sāvitrī and the mantras like it really belong further along, in the positions of the heart and the other limbs -- but the text pulls them forward, right to the start, to make clear they count as limbs at all. That the beginning and the ending of the passage agree on this is exactly how we know the whole teaching holds together as one thing, not several. When the text says these three -- the Sāvitrī, the Praṇava, the Lakṣmī verse -- are not to be given to 'woman-and-Śūdra,' notice what that phrase is doing: even while it forbids handing over these three particular mantras, it quietly confirms that a woman or a Śūdra is otherwise entitled to the main worship itself. The line about the thirty-two-syllable chant simply ties those syllables to the chant -- the rest repeats what we already know. And the warning that follows -- if such a person learns these anyway, they fall to hell when they die -- isn't a new rule; it's the old prohibition, given teeth. The same goes for the teacher: 'never teach this, ever' means exactly that, and the warning that a teacher who breaks this falls the same way is not a separate threat, just the same one, stated once more so it holds.
Close to the Sanskrit
Here indeed there are six questions; the group of four already answered, taken together, yields both the priority of the limbs and the fruit that belongs to the limbs -- the meaning already stated by 'therefore one should know this sāman together with its limb; he who knows it attains immortality.' As for the mantras beginning with the Sāvitrī, which properly belong in the place of the limbs beginning with the heart -- the fact that they are drawn forward right at the outset, for the purpose of enjoining their status as limbs, shows, by the agreement of the beginning and the conclusion, the intention that the teaching is one. By saying 'they do not wish [to impart] the Sāvitrī, the Praṇava, and the Yajus called Lakṣmī to a woman-and-Śūdra' -- where 'woman-and-Śūdra' means woman and Śūdra taken together -- the text, while making a prohibition addressed to that woman or Śūdra, thereby shows that a woman or Śūdra does have eligibility for the principal worship [itself]. 'One should know the thirty-two syllabled sāman' enjoins the connection of the thirty-two syllables with the sāman; 'he who knows...' has the meaning already stated. 'If a woman or Śūdra should come to know the Sāvitrī, the Lakṣmī, and the Yajus that is the Praṇava, that one, having died, goes down to hell' -- by pointing out the resultant harm, this only reinforces the prohibition. 'Therefore he should never declare it' shows the teacher's prohibition, meaning 'let him never, on any occasion, declare it.' 'If he does declare it, he is [called] a teacher, and by that very declaration, having died, he goes downward' -- by pointing out the resultant harm, this again only reinforces the same prohibition.