Bhashya
ये पुनः मन्त्रब्राह्मणलक्षणेन वेदानुवचनेन प्रकाश्यमानं विविदिषन्ति-इति व्याचक्षते, तेषाम् आरण्यकमात्रमेव वेदानुवचनं स्यात् ; न हि कर्मकाण्डेन पर आत्मा प्रकाश्यते ; 'तं त्वौपनिषदम्' इति विशेषश्रुतेः ।वेदानुवचनेनेति च अवि-शेषितत्वात् समस्तग्राहि इदं वचनम् ; न च तदेकदेशोत्सर्गो युक्तः ।ननु त्वत्पक्षेऽपि उपनिषद्वर्जमिति एकदेशत्वं स्यात्— न, आद्यव्याख्याने अविरोधात् अस्मत्पक्षे नैष दोषो भवति ; यदा वेदानुवचनशब्देन नित्यः स्वाध्यायो विधीयते, तदा उपनिषदपि गृहीतैवेति, वेदानुवचनशब्दार्थैकदेशो न परित्यक्तो भवति ।यज्ञादिसहपाठाच्च— यज्ञादीनि कर्माणि एव अनुक्रमिष्यन् वेदानुवचनशब्दं प्रयुङ्क्ते ; तस्मात् कर्मैव वेदानुवचनशब्देनोच्यत इति गम्यते ; कर्म हि नित्यस्वाध्यायः ॥
In plain words
There is another reading worth setting straight. Some explain the passage this way: people seek to know the Self as it is made visible through vedānuvacana -- meaning the study of mantra and brāhmaṇa together. But on that reading, vedānuvacana would shrink down to just the forest treatises, the āraṇyaka portion, since the ritual section of the Veda by itself never reveals the supreme Self; scripture is specific about that -- 'him, though, as taught in the Upaniṣad.' Here is the problem: the word vedānuvacana carries no such restriction anywhere in the text, so it has to cover everything, and cutting off a piece of that meaning is not something you get to do. You might object: but doesn't your own reading exclude the Upaniṣad too, and end up just as partial? No. That problem belongs to the other explanation, not to ours. On our reading, when the word vedānuvacana enjoins the permanent daily recitation, the Upaniṣad is swept in along with everything else -- nothing in the word's meaning gets left outside. And there is a further sign pointing the same way: the word is listed right alongside sacrifice and the other rites, at the very point where the text is about to run through them one by one -- which is why the word vedānuvacana, in that sentence, has to mean action itself. Because that is exactly what this daily, permanently enjoined recitation is: an action.
Close to the Sanskrit
Now, those who explain it thus -- 'they seek to know [the Self] as being illumined by vedānuvacana, characterized as the mantra and the brāhmaṇa [portions]' -- for them, vedānuvacana would amount to the āraṇyaka texts only; for the supreme Self is not illumined by the ritual section [alone]; because of the specific scriptural statement, 'but him, as taught in the Upaniṣad'. And since [the term] 'vedānuvacana' is unqualified, this statement covers everything; and it is not right to abandon a part of that [full meaning]. [Objection:] But even on your view, since the Upaniṣad would be excluded, there would likewise be a restriction to a part! [Reply:] No -- because on the first explanation [ours] there is no such contradiction, this fault does not arise on our side; for when by the word 'vedānuvacana' the permanent daily recitation is enjoined, then the Upaniṣad too is included, so no part of the meaning of the word vedānuvacana is left out. And because of being read together with sacrifice and the like: about to enumerate sacrifice and other such actions in order, [the text] employs the word vedānuvacana; therefore it is understood that action alone is meant by the word vedānuvacana; for action, here, is precisely the permanent daily recitation.