Chandogya Upanishad 8.11

1. ‘Now, when one is sound asleep, composed, serene, and knows no dream—that is the Self (Ātman),’ said he. ‘That is the immortal, the fearless. That is Brahma.’

Then with tranquil heart he went forth.

Then, even before reaching the gods, he saw this danger: ‘Assuredly, indeed, this one does not exactly know himself (ātmānam) with the thought “I am he,” nor indeed the things here. He becomes one who has gone to destruction. I see nothing enjoyable in this.’

2. Fuel in hand, back again he came. Then Prajāpati said to him: ‘Desiring what, O Maghavan, have you come back again, since you went forth with tranquil heart?’

Then he [i. e. Indra] said: ‘Assuredly, this [self] does not exactly know himself with the thought “I am he,” nor indeed

the things here. He becomes one who has gone to destruction. I see nothing enjoyable in this.’

3. ‘He is even so, O Maghavan,’ said he. ‘However, I will explain this further to you, and there is nothing else besides this. Live with me five years more.’

Then he lived with him five years more.—That makes one hundred and one years. Thus it is that people say, ‘Verily, for one hundred and one years Maghavan lived the chaste life of a student of sacred knowledge (brahmacarya) with Prajāpati.’—

To him [i.e. to Indra] he [i.e. Prajāpati] then said:—