Śatapatha Brāhmaṇa ("of a hundred paths") 1.2.1.12

1.2.1.12

atha yaddakṣiṇatastadupapadhāti | viśvābhyastvāśābhya upadadhāmīti sa yadimāṃllokānati caturthamasti vā na vā tenaivaitaddviṣantam bhrātṛvyamavabādhate 'naddhā vai tadyadimāṃllokānati caturthamasti vā na vānaddho tadyadviśvā āśāstasmādāha viśvābhyastvāśābhya upadadhāmīti tūṣṇīṃ vaivetarāṇi kapālānyupadadhāti cita sthordhvacita iti vā

He now puts on the one that is (to stand) on the right (i.e. south of the first), with the text (Vâg. S. I, 18 d): 'For all the regions I put thee on!' What fourth (world) there is or is not beyond these (three) worlds, by that indeed he thereby chases away the spiteful enemy. Uncertain, no doubt, is what fourth (world) there is or is not beyond these (three) worlds, and uncertain also are all those regions; for this reason he says, 'For all the regions I put thee on!' The remaining potsherds he puts on either silently, or with the text (Vâg. S. I, 18 e): 'Layer-forming are ye! heap-forming are ye!'