Shatapatha Brahmana 9.5.1.36

9.5.1.36

yadvevaitāni havīṃṣi nirvapati | diśa eṣo 'gnistā u evāmūḥ purastāddarbhastambaṃ ca logeṣṭakāścopadadhāti tāḥ prāṇabhṛtaḥ prathamāyāṃ citau sarvaiva dvitīyā sarvā tṛtīyā sarvā caturthyatha pañcamyai citerasapatnā nākasadaḥ pañcacūḍāstā ūrdhvā utkrāmantya āyaṃstābhyaḥ prajāpatirabibhetsarvaṃ vā idamimāḥ parācyo 'tyeṣyantīti tā dhātā bhūtvā paryagacattāsu pratyatiṣṭhat

And, again, as to why he prepares these oblations. This Agni (the fire-altar) is the quarters (regions), and these he lays down beforehand (in the shape of) the bunch of Darbha grass and the clod-bricks; the Prânabhrits in the first layer, the whole of the second, the whole of the third, and the whole of the fourth (layers); and of the fifth layer the Asapatnâs, Nâkasads and Pañkakûdâs,--these kept going out upwards (from Pragâpati, the altar). Pragâpati was afraid of them, thinking, 'Whilst moving away, these will go beyond this universe.' Having become the Orderer, he went round them and established himself in them.