ChU 1.11.8
अथ हैनं प्रतिहर्तोपससाद । प्रतिहर्तर् या देवता प्रतिहारम् अन्वायत्ता तां चेद् अविद्वान् प्रतिहरिष्यसि मूर्धा ते विपतिष्यतीति मा भगवान् अवोचत् । कतमा सा देवतेति
atha hainaṃ pratihartopasasāda | pratihartar yā devatā pratihāram anvāyattā tāṃ ced avidvān pratihariṣyasi mūrdhā te vipatiṣyatīti mā bhagavān avocat | katamā sā devateti
Devanagari rendered by HREEM from the edition's roman (IAST) text; the IAST is the edition's own.
Then the Pratihartri approached him, saying: 'Sir, you said to me, "Pratihartri, if you, without knowing the deity belonging to the pratihâra, are going to sing it, your head will fall off,"—which then is that deity?'
Translated by F. Max Müller