CHĀNDOGYA UPANISHAD · 4.2.5

तस्या ह मुखम् उपोद्गृह्णन्न् उवाचाजहारेमाः शूद्रानेनैव मुखेनालापयिष्यथा इति ।
ते हैते रैक्वपर्णा नाम महावृषेषु यत्रास्मा उवास ।
तस्मै होवाच ॥

tasyā ha mukham upodgṛhṇann uvācājahāremāḥ śūdrānenaiva mukhenālāpayiṣyathā iti ।
te haite raikvaparṇā nāma mahāvṛṣeṣu yatrāsmā uvāsa ।
tasmai hovāca ॥

He, opening her mouth, said: 'You have brought these (cows and other presents), O Sûdra, but only by that mouth did you make me speak.' These are the Raikva-parna villages in the country of the Mahâvrishas (mahâpunyas) where Raikva dwelt under him. And he said to him:

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