Chandogya Upanishad 1.7.8

1.7.8

athānenaiva ye caitasmād arvāñco lokās tāṃś cāpnoti manuṣyakāmāṃś ca \
tasmād u haivaṃvid udgātā brūyāt \\107.8\

8. Through the latter he wins the worlds which are under the latter, and also men's desires. Therefore an Udgātṛi priest who knows this may say: 'What desire may I win for you by singing?' For truly he is lord of the winning of desires by singing, who, knowing this, sings the Sāman—yea, sings the Sāman!