Atharvaveda 4.1.1

4.1.1

bráhma jajñānáṃ prathamáṃ purástād ví sīmatáḥ surúco vená āvaḥ |
sá budhnyā̀ upamā́ asya viṣṭhā́ḥ satáś ca yónim ásataś ca ví vaḥ ||1||

The bráhman that was first born of old (purástāt; in the east?) Vena hath unclosed from the well-shining edge (sīmatás; horizon?); he unclosed the fundamental nearest shapes (viṣṭhā́) of it, the womb (yóni) of the existent and of the non-existent.