Śatapatha Brāhmaṇa ("of a hundred paths") 6.1.2.35

6.1.2.35

atho gauriti brūyāt | ime vai lokā gauryaddhi kiṃ ca gacatīmāṃstallokāngacatīma u lokā eṣo 'gniścitastasmādgauriti brūyāt

Or he may say, 'A cow (or bullock, go);--'the cow forsooth means these worlds, for whatever walks (gam) that walks in these worlds; and that fire also is these worlds: therefore he may say, 'A cow.'