Shatapatha Brahmana 8.7.1.3

8.7.1.3

yadveva 'rtavyā upadadhāti | saṃvatsara eṣo 'gniḥ sa ṛtavyābhiḥ saṃhitaḥ saṃvatsaramevaitadṛtubhiḥ saṃtanoti saṃdadhāti tā vai nānāprabhṛtayaḥ samānodarkā ṛtavo vā asṛjyanta te sṛṣṭā nānaivāsan

And, again, as to why he lays down seasonal (bricks),--this fire-altar is the year, and it is joined together by means of the seasonal (bricks): he thus makes the year continuous, and joins it together, by means of the seasons. These (formulas of the seasonal bricks) begin in a different way, but end in the same way; for the seasons were created, and, when created, they were different.