Prashna Upanishad
Then Sukesas Bhâradvâga asked him, saying: "Sir, Hiranyanâbha, the prince of Kosalâ, came to me and asked this question: Do you know the person of sixteen parts, O Bhâradvâga? I said to the prince: I do not know him; if I knew him, how should I not tell you? Surely, he who speaks what is untrue withers away to the very root; therefore I will not say what is untrue. Then he mounted his chariot and went away silently. Now I ask you, where is that person?"
He replied: "Friend, that person is here within the body, he in whom these sixteen parts arise.
He reflected: What is it by whose departure I shall depart, and by whose staying I shall stay?
He sent forth (created) Prâna (spirit); from Prâna Sraddhâ (faith), ether, air, light, water, earth, sense, mind, food; from food came vigour, penance, hymns, sacrifice, the worlds, and in the worlds the name also.
As these flowing rivers that go towards the ocean, when they have reached the ocean, sink into it, their name and form are broken, and people speak of the ocean only, exactly thus these sixteen parts of the spectator that go towards the person (purusha), when they have reached the person, sink into him, their name and form are broken, and people speak of the person only, and he becomes without parts and immortal. On this there is this verse:
That person who is to be known, he in whom these parts rest, like spokes in the nave of a wheel, you know him, lest death should hurt you."
Then he (Pippalâda) said to them: "So far do I know this Highest Brahman, there is nothing higher than it."
And they praising him, said: "You, indeed, are our father, you who carry us from our ignorance to the other shore." Adoration to the highest Rishis! Adoration to the highest Rishis! Tat sat. Harih, Om!