CHĀNDOGYA UPANISHAD · 6.1.3

श्वेतकेतो यन् नु सोम्येदं महामना अनूचानमानी स्तब्धो ऽसि ।
उत तम् आदेशम् अप्राक्ष्यः येनाश्रुतं श्रुतं भवत्य् अमतं मतम् अविज्ञातं विज्ञातम् इति ।
कथं नु भगवः स आदेशो भवतीति ॥

śvetaketo yan nu somyedaṃ mahāmanā anūcānamānī stabdho ’si ।
uta tam ādeśam aprākṣyaḥ yenāśrutaṃ śrutaṃ bhavaty amataṃ matam avijñātaṃ vijñātam iti ।
kathaṃ nu bhagavaḥ sa ādeśo bhavatīti ॥

His father said to him: 'Svetaketu, as you are so conceited, considering yourself so well-read, and so stern, my dear, have you ever asked for that instruction by which we hear what cannot be heard, by which we perceive what cannot be perceived, by which we know what cannot be known?'

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