Śatapatha Brāhmaṇa ("of a hundred paths") 7.3.1.47

7.3.1.47

athātāḥ sampadeva | catasro logeṣṭakā upadadhāti ṣaḍṛcena nivapati dvābhyāmāpyāyayati taddvādaśa dvādaśa māsāḥ saṃvatsaraḥ saṃvatsaro 'gniryāvānagniryāvatyasya mātrā tāvattadbhavati

Now then the (mystic) correspondence,--four clod-bricks he puts on; with a six-versed (hymn) he scatters (the sand); with two (verses) he makes (the seed) grow; that makes twelve,--twelve months are a year, and the year is Agni: as great as Agni is, as great as is his measure, so great does this become.