दुग्धेऽस्मै वाग्दोहं यो वाचो दोहोऽन्नवानन्नादो भवति य एतामेवंसाम्नामुपनिषदं वेदोपनिषदं वेदेति ॥ १.१३.४ ॥
In plain words
For him speech yields its milk, which is the milk of speech; and he becomes one who has food and eats food, who knows this secret doctrine of the Sāmans — who knows the secret doctrine.
The commentators
Chāndogyopaniṣadbhāṣyam
स्तोभाक्षरोपासनाफलमाह—
दुग्धेऽस्मै वाग्दोहमित्याद्युक्तार्थम् । य एतामेव यथोक्तल क्षणां साम्नां सामावयवस्तोभाक्षरविषयाम् उपनिषदं दर्शनं वेद, तस्य एतद्यथोक्तं फलमित्यर्थः । द्विरभ्यास अध्यायपरि समाप्त्यर्थः । सामावयवविषयोपासनाविशेषपरिसमाप्त्यर्थ इति-शब्द इति ॥
In plain words
The text explains the fruit of meditating upon the stobha syllables.
The meaning of the passage beginning with 'Speech yields its milk...' is clear. Whoever understands this secret doctrine of the Samans—focused on the stobha syllables that form parts of the chants—receives the fruit just described. The repetition of the word 'veda' at the end marks the conclusion of the chapter and the completion of this specific meditation on the parts of the Samans. Thus ends the section.
Close to the Sanskrit
He states the fruit of meditation upon the stobha syllables.
The passage beginning with 'dugdhe 'smai vāgdoham' has its meaning explained. Whoever knows this secret doctrine of the samans having the characteristics mentioned before, concerning the stobha syllables which are parts of the samans, of him this is the previously stated fruit—this is the meaning. The double repetition is for the purpose of concluding the chapter and for concluding the particular meditation concerning the parts of the samans, thus is the word 'iti'.