CHĀNDOGYA UPANISHAD · 2.8.3

दुग्धे ऽस्मै वाग् दोहं यो वाचो दोहः ।
अन्नवान् अन्नादो भवति ।
य एतद् एवं विद्वान् वाचि सप्तविधं सामोपास्ते ॥

dugdhe ’smai vāg dohaṃ yo vāco dohaḥ ।
annavān annādo bhavati ।
ya etad evaṃ vidvān vāci saptavidhaṃ sāmopāste ॥

Speech yields the milk, which is the milk of speech itself, to him who knowing this meditates on the sevenfold Sâman in speech. He becomes rich in food, and able to eat food.

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)