Śatapatha Brāhmaṇa ("of a hundred paths") 10.4.3.21

10.4.3.21

taddhaike āhavanīya evaitāṃ sampadamāpipayiṣantyanye vā ete'gnayaścitāḥ kimanyatropahitā iha sampaśyemeti na tathā kuryāddaśa vā etānagnīṃścinute'ṣṭau dhiṣṇyānāhavanīyaṃ ca gārhapatyaṃ ca tasmādāhurvirāḍagniriti daśākṣarā hi virāṭ tānnu sarvānekamivaivācakṣate'gnirityetasya hyevaitāni sarvāṇi rūpāṇi yathā saṃvatsarasyāhorātrāṇyardhamāsā māsā ṛtava evamasyaitāni sarvāṇi rūpāṇi

Now, some wish to get this total amount in the Âhavanîya itself, arguing, 'Those are different brick-built fire-altars: why should we here (in the Âhavanîya altar) take into account those laid down there (in the Gârhapatya and Dhishnyas)?' But let him not do so. There are, indeed, ten of these fire-altars he builds--eight Dhishnyas, the Âhavanîya and the Gârhapatya--whence they say, 'Agni is Virâg (wide shining or ruling),' for the Virâg (metre) consists of ten syllables: but, surely, all these (altars and hearths) are looked upon as only one, as Agni; for it is merely forms of him that they all are,--even as the days and nights, the half-moons, the months, and the seasons (are forms) of the year, so are they all forms of him (Agni).