Śatapatha Brāhmaṇa ("of a hundred paths") 6.5.2.17

6.5.2.17

saiṣā gaureva | ime vai lokā ukheme lokā gaustasyā etadūdho yaiṣā tiraścī rāsnā sā vitṛtīye bhavati vitṛtīye hi gorūdhaḥ

This (fire-pan) indeed is a cow, for the fire-pan is these worlds, and these worlds are a cow: that horizontal belt is its udder; it is in the (upper) third of it, for the udder is in one-third of the cow.