BṚHADĀRAṆYAKA UPANISHAD · 1.5.5

त्रयो वेदा एत एव ।
वाग् एवर्ग्वेदो मनो यजुर्वेदः प्राणः सामवेदः ॥

trayo vedā eta eva ।
vāg evargvedo mano yajurvedaḥ prāṇaḥ sāmavedaḥ ॥

These are the three Vedas: the Rig-veda is speech, the Yagur-veda mind, the Sâma-veda breath.

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