CHĀNDOGYA UPANISHAD · 1.5.5

अथ खलु य उद्गीथः स प्रणवो यः प्रणवः स उद्गीथ इति ।
होतृषदनाद् ध एवापि दुरुद्गीथम् अनुसमाहरतीत्य् अनुसमाहरतीति ॥

atha khalu ya udgīthaḥ sa praṇavo yaḥ praṇavaḥ sa udgītha iti ।
hotṛṣadanād dha evāpi durudgītham anusamāharatīty anusamāharatīti ॥

He who knows that the udgîtha is the pranava, and the pranava the udgîtha, rectifies from the seat of the Hotri priest any mistake committed by the Udgâtri priest in performing the udgîtha, yea, in performing the udgîtha.

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