Chandogya Upanishad 6.7

न वै नूनं भगवन्तस्त एतदवेदिषुर्यद्ध्येतदवेदिष्यन्कथं मे नावक्ष्यन्निति भगवाँस्त्वेव मे तद्ब्रवीत्विति तथा सोम्येति होवाच ॥ ७ ॥

6.1.7 — na vai nunam bhagavantasta etadavedishuryaddhyetadavedishyankatham me navakshyanniti bhagavanstveva me tadbravitviti tatha somyeti hovacha || 7 ||

The son said: 'Surely those venerable men (my teachers) did not know that. For if they had known it, why should they not have told it me? Do you, Sir, therefore tell me that.' 'Be it so,' said the father.

(श्वेतकेतु ने कहा —) 'निश्चय ही मेरे पूज्य गुरुजनों ने यह नहीं जाना था; यदि जानते तो मुझे क्यों न कहते? अतः हे भगवन्, आप ही मुझे यह बताएँ।' पिता ने कहा — 'हे सौम्य, ऐसा ही हो।'