Śatapatha Brāhmaṇa ("of a hundred paths") 7.1.1.13

7.1.1.13

yadvevainam pariśridbhiḥ pariśrayati | ayaṃ vai loko gārhapatya āpaḥ pariśrita imaṃ taṃ lokamadbhiḥ paritanoti samudreṇa hainaṃ tatparitanoti sarvatastasmādimaṃ lokaṃ sarvataḥ samudraḥ paryeti dakṣiṇāvṛttasmādimaṃ lokaṃ dakṣiṇāvṛtsamudraḥ paryeti khātena tasmādimaṃ lokaṃ khātena samudraḥ paryeti

And, again, why he encloses it with enclosing-stones;--the Gârhapatya hearth is this (terrestrial) world, and the enclosing-stones are the waters: he thus surrounds this world with water,--it is with the ocean that he thus surrounds it on all sides, and hence the ocean flows round this world on all sides. (He puts up the stones) by turning to the right (or south), whence the ocean flows round this world (from the east) southwards;--by means of a dug out (hole, or moat), whence the ocean flows round this world in a moat.