Verse 1.13.4

दुग्धेऽस्मै वाग्दोहं यो वाचो दोहोऽन्नवानन्नादो भवति य एतामेवंसाम्नामुपनिषदं वेदोपनिषदं वेदेति ॥ १.१३.४ ॥
॥ इति त्रयोदशः खण्डः ॥
॥ इति प्रथमोऽध्यायः ॥

dugdhe'smai vāgdohaṃ yo vāco doho'nnavānannādo bhavati ya etāmevaṃsāmnāmupaniṣadaṃ vedopaniṣadaṃ vedeti || 1.13.4 ||
|| iti trayodaśaḥ khaṇḍaḥ ||
|| iti prathamo'dhyāyaḥ ||

4. To a person who knows the Sāma with its stobhas, as mentioned earlier, the organ of speech gives of its best. Such a person gets plenty of food to eat and can also eat much food.

Word-for-word explanation:

Yaḥ, that person who; etām evam, this as stated earlier; sāmnām, the Sāma with its stobhas; upaniṣadam, the science of it; veda, knows; vācaḥ, of the organ of speech; yaḥ dohaḥ, the essence; doham, [that] essence; vāk, the organ of speech; asmai, to him [who knows]; dugdhe, gives; [saḥ, he]; annavān, rich with food; annādaḥ, a great eater of food; bhavati, becomes. Iti trayodaśaḥ khaṇḍaḥ, here ends the thirteenth section. Iti chāndogya upaniṣadi prathamaḥ adhyāyaḥ, here ends the first chapter of the Chāndogya Upaniṣad.

Commentary:

In the previous verses, mention was made of the stobhas. Now the benefit of meditating on them is being described. A person who knows the real import of those stobhas receives the best that the organ of speech has to offer.