Śatapatha Brāhmaṇa ("of a hundred paths") 5.2.3.5

5.2.3.5

atha yadaṣṭākapālo bhavati | aṣṭākṣarā vai gāyatrī gāyatrī vā iyam pṛthivyatha yatsamānasya haviṣa ubhayatra juhotyeṣā hyevaitadubhayaṃ tasya vāso dakṣiṇā yadvai savāsā araṇyaṃ nodāśaṃsate nidhāya vai tadvāso 'timucyate tatho hainaṃ sūyamānamāsaṅgo na vindati

And as to why it is a (cake) on eight potsherds,--the Gâyatrî consists of eight syllables, and this earth is Gâyatrî. And as to why he offers of the same sacrificial food both (oblations): thereby, indeed, both of it comes to be this latter one (viz. Anumati, or approval). A garment is the sacrificial fee for this (offering): for even as one clad in a garment does not venture into the forest, but having deposited that garment (somewhere) escapes (robbers), in like manner no assault befalls him while being consecrated.