ChU 7.20.1
यदा वै निस्तिष्ठत्य् अथ श्रद्दधाति । नानिस्तिष्ठञ् छ्रद्दधाति । निस्तिष्ठन्न् एव श्रद्दधाति । निष्ठा त्व् एव विजिज्ञासितव्येति । निष्ठां भगवो विजिज्ञास इति
yadā vai nistiṣṭhaty atha śraddadhāti | nānistiṣṭhañ chraddadhāti | nistiṣṭhann eva śraddadhāti | niṣṭhā tv eva vijijñāsitavyeti | niṣṭhāṃ bhagavo vijijñāsa iti
Devanagari rendered by HREEM from the edition's roman (IAST) text; the IAST is the edition's own.
'When one attends on a tutor (spiritual guide), then one believes. One who does not attend on a tutor, does not believe. Only he who attends, believes. This attention on a tutor, however, we must desire to understand.' 'Sir, I desire to understand it.'
Translated by F. Max Müller