Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.1.7

8.7.1.7

tadyadete atropadadhāti | saṃvatsara eṣo 'gnirima u lokāḥ saṃvatsarastasya dyaureva pañcamī citirdyaurasya śiśira ṛtustadyadete atropadadhāti yadevāsyaite ātmanastadasminnetatpratidadhāti tasmādete atropadadhāti

And as to why he now lays down these two;--this fire-altar is the year, and the year is these worlds: the fifth layer of this (altar) is the sky, and the dewy season of this (year) is the sky; and when he now lays down these two (bricks), he thereby restores to his (Agni's) body what these two are thereto: this is why he now lays down these two (bricks).