CHĀNDOGYA UPANISHAD · 4.10.2

तं जायोवाच तप्तो ब्रह्मचारी कुशलम् अग्नीन् परिचचारीत् ।
मा त्वा अग्नयः परिप्रवोचन् ।
प्रब्रूह्य् अस्मा इति ।
तस्मै हाप्रोच्यैव प्रवासां चक्रे ॥

taṃ jāyovāca tapto brahmacārī kuśalam agnīn paricacārīt ।
mā tvā agnayaḥ paripravocan ।
prabrūhy asmā iti ।
tasmai hāprocyaiva pravāsāṃ cakre ॥

Then his wife said to him: 'This student, who is quite exhausted (with austerities), has carefully tended your fires. Let not the fires themselves blame you, but teach him.' The teacher, however, went away on a journey without having taught him.

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