BṚHADĀRAṆYAKA UPANISHAD · 1.3.27

तस्य हैतस्य साम्नो यः प्रतिष्ठां वेद प्रति ह तिष्ठति ।
तस्य वै वाग् एव प्रतिष्ठा ।
वाचि हि खल्व् एष एतत् प्राणः प्रतिष्ठितो गीयते ।
अन्न इत्य् उ हैक आहुः ॥

tasya haitasya sāmno yaḥ pratiṣṭhāṃ veda prati ha tiṣṭhati ।
tasya vai vāg eva pratiṣṭhā ।
vāci hi khalv eṣa etat prāṇaḥ pratiṣṭhito gīyate ।
anna ity u haika āhuḥ ॥

He who knows what is the support of that Sâman, he is supported. Now verily its support is speech only. For, as supported in speech, that breath is sung as that Sâman. Some say the support is in food.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)