CHĀNDOGYA UPANISHAD · 1.10.8

तत्रोद्गात्ःन् आस्तावे स्तोष्यमाणान् उपोपविवेश ।
स ह प्रस्तोतरम् उवाच ॥

tatrodgātḥn āstāve stoṣyamāṇān upopaviveśa ।
sa ha prastotaram uvāca ॥

He went and sat down on the orchestra near the Udgâtris, who were going to sing their hymns of praise. And he said to the Prastotri (the leader):

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