Shatapatha Brahmana 14.1.3.14

14.1.3.14

athottarataḥ sikatā upakīrṇā bhavanti tadrajatam hiraṇyamadhastādupāsyati pṛthivyāḥ saṃspṛśaspāhītyetadvai devā abibhayuryadvai na imamadhastādrakṣāṃsi nāṣṭrā na hanyurityagnervā etadreto yaddhiraṇyaṃ nāṣṭrāṇāṃ rakṣasāmapahatyā atho pṛthivyu ha vā etasmādbibhayāṃ cakāra yadvai māyaṃ taptaḥ śuśucāno na hiṃsyāditi tadevāsyā etadantardadhāti rajatam bhavati rajataiva hīyam pṛthivī

Now sand has been strewed on the north side of it: below that he (previously) throws (a plate of) white gold, with, 'Protect it from contact with the earth!' For at that time the gods were afraid lest the Rakshas, the fiends, might injure that (Pravargya) of theirs from below; and that, to wit, gold, being Agni's seed, it (serves) for repelling the fiends, the Rakshas. But, indeed, the Earth also was afraid of this lest this (Pravargya), when heated and glowing, might injure her: he thus keeps it separate from her. White it is, for white, as it were, is this earth.