CHĀNDOGYA UPANISHAD · 4.16.4

अथ यत्र उपाकृते प्रातरनुवाके न पुरा परिधानीयाया ब्रह्मा व्यववदत्य् उभे एव वर्तनी संस्कुर्वन्ति ।
न हीयते ऽन्यतरा ॥

atha yatra upākṛte prātaranuvāke na purā paridhānīyāyā brahmā vyavavadaty ubhe eva vartanī saṃskurvanti ।
na hīyate ’nyatarā ॥

But when after the Prâtaranuvâka ceremony has begun, and before the recitation of the Paridhânîyâ hymn, the Brahman priest has not (to break his silence and) to speak, they perform both ways perfectly, and neither of them is injured.

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