Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.3.18

2.3.3.18

prajāpatirvā agniḥ | saṃvatsaro vai prajāpatiḥ saṃvatsare-saṃvatsare ha vā asyāgnihotraṃ cityenāgninā saṃtiṣṭhate saṃvatsare-saṃvatsare cityamagnimāpnoti ya evaṃ vidvānagnihotraṃ juhotyetadu hāsyāgnihotraṃ cityenāgninā saṃtiṣṭhate cityamagnimāpnoti

The fire, assuredly, is Pragâpati,--and Pragâpati is the year. Year after year, therefore, is his Agnihotra consummated with the piled-up fire-altar; and year after year does he obtain the piled-up fire altar, whosoever, knowing this, offers the Agnihotra.