Bhashya
तामेतां सावित्रीं ह एके शाखिनः अनुष्टुभम् अनुष्टुप्प्र-भवाम् अनुष्टुप्छन्दस्काम् अन्वाहुरुपनीताय ।तदभिप्राय-माह— वाक् अनुष्टुप्, वाक्च शरीरे सरस्वती, तामेव हिवाचं सरस्वती माणवकायानुब्रूम इत्येतद्वदन्तः ।न तथाकुर्यात् न तथा विद्यात्, यन् ते आहुः मृषैव तत् ;किं तर्हि गायत्रीमेव सावित्रीमनुब्रूयात् ; कस्मात् ? य-स्मात् प्राणो गायत्रीत्युक्तम् ; प्राणे उक्ते, वाक्च सरस्वतीच अन्ये च प्राणाः सर्व माणवकाय समर्पितं भवति ।किं-चेदं प्रासङ्गिकमुक्त्वा गायत्रीविदं स्तौति-- यदि ह वै अपिएवंवित् बह्विव- न हि तस्य सर्वात्मनो बहु नामास्ति किं-चित् , सर्वात्मकत्वाद्विदुषः- प्रतिगृह्णाति, न हैव तत् प्रति-ग्रहजातं गायत्र्या एकंचन एकमपि पदं प्रति पर्याप्तम् ॥
In plain words
This same Sāvitrī gets recited by some as if she were nothing more than the Anuṣṭubh metre — their reasoning being: speech is Anuṣṭubh, speech in the body is Sarasvatī, so reciting to the pupil is just reciting speech. Don't follow that reasoning, and don't believe it either — it's simply wrong. Recite the Gāyatrī as the Sāvitrī, full stop. Why? Because the breath of life has already been named Gāyatrī, and naming the breath brings speech, Sarasvatī, and every other faculty along with it — the whole of the pupil is handed over in that one word. And having mentioned that in passing, the teaching turns to praise the one who knows her: hand such a person what looks like everything, and it is still nothing to him, because his very self is everything already — nothing can be 'much' to someone who is the Self of all. Whatever he receives, the whole pile of it, doesn't add up to even one foot of the Gāyatrī.
Close to the Sanskrit
This very Sāvitrī, some followers of a [Vedic] branch recite to the initiated pupil as the Anuṣṭubh, born of Anuṣṭubh, having Anuṣṭubh as its metre. Their intention is stated thus: 'Speech is Anuṣṭubh, and speech in the body is Sarasvatī; that very speech, Sarasvatī, we recite to the pupil' — so say those who assert this. One should not do so, one should not think so; what they say is simply false. What then? One should recite the Gāyatrī itself as the Sāvitrī. Why? Because it has been stated that prāṇa is Gāyatrī. When prāṇa is so stated, speech, Sarasvatī, and the other breaths — all of them — become entrusted to the pupil at once. Moreover, having said this in passing, [the text] praises the knower of Gāyatrī: 'If, indeed, such a knower should even accept what looks like much' — for one whose Self is everything has nothing that counts as 'much,' since a knower's nature is to be the Self of all — 'that whole mass of gift received is indeed not sufficient even for a single foot of the Gāyatrī.'