Taittirīya Upaniṣad 1.6.1

1.6.1

sa ya eṣo 'ntarahṛdaya ākāśaḥ /
tasminnayaṃ puruṣo manomayaḥ /
amṛto hiraṇmayaḥ /
antareṇa tāluke /
ya eṣa stana ivāvalaṃbate /
sendrayoniḥ /
yatrāsau keśānto vivartate /
vyapohya śīrṣakapāle /
bhūrityagnau pratitiṣṭhati /
bhuva iti vāyau // 1//

In the space that there is in the heart, is this Person who is realisable through knowledge, and who is immortal and effulgent. This thing that hangs down between the palates like a teat, through it runs the path of Brahman; and reaching where the hairs part, it passes out by separating the skulls. (Passing out through that path, a man) becomes established in Fire as the Vyāhṛti Bhūḥ; he becomes established in Air as the Vyāhṛti Bhuvaḥ; in the Sun as the Vyāhṛti Svaḥ; in Brahman as the Vyāhṛti Mahaḥ. He himself gets independent sovereignty; he attains the lord of the mind; he becomes the ruler of speech, the ruler of eyes, the ruler of ears, the ruler of knowledge. Over and above all these he becomes Brahman which is embodied in ākāśa, which is identified with the gross and the subtle and has truth as Its real nature, which revels in life, under whose possession the mind is a source of bliss, which is enriched with peace and is immortal. Thus, O Prācīnayogya, you worship.