Śatapatha Brāhmaṇa ("of a hundred paths") 9.1.2.31

9.1.2.31

saptabhirvikarṣati | saptacitiko 'gniḥ sapta 'rtavaḥ saṃvatsaraḥ saṃvatsaro 'gniryāvānagniryāvatyasya mātrā tāvataivainametadvikarṣati taṃ vaṃśamutkarenyasya

With seven (formulas) he draws them across,--the altar consists of seven layers, and seven seasons are a year, and Agni is the year: as great as Agni is, as great as is his measure, with so much he thus crosses him. Having thrown the cane on the heap of rubbish;--