Shatapatha Brahmana 6.7.1.16

6.7.1.16

athainaṃ śikyena bibharti | ime vai lokā eṣo 'gnirdiśaḥ śikyaṃ digbhirhīme lokāḥ śaknuvanti sthātuṃ yacaknuvanti tasmācikyaṃ digbhirevainametadbibharti ṣaḍudyāmam bhavati ṣaḍḍhi diśo mauñjaṃ trivṛttasyokto bandhurmṛdā digdhaṃ tasyo evokto 'tho anatidāhāya

Now he carries him (Agni, the fire) by means of a netting --he, Agni, is these worlds, and the netting is the regions, for by means of the regions these worlds are able to stand; and inasmuch as they are so able (sak), it is called a netting (sikya): he thus carries him by means of the regions. It is furnished with six strings,--for there are six regions;--made of reed-grass, triply wound--the significance of this has been explained;--and smeared with clay--(the significance) of this also has been explained; but it also serves to keep them from taking fire.