Śatapatha Brāhmaṇa ("of a hundred paths") 1.2.2.16

1.2.2.16

yadā śṛto 'thābhivāsayati | nedenamupariṣṭānnāṣṭrā rakṣāṃsyavapaśyāniti nedveva nagna iva muṣita iva śayātāityu caiva tasmādvā abhivāsayati

When it is done, he covers it over (with hot ashes): 'Lest the evil spirits, the Rakshas, should espy it,' thus (he thinks) and 'Lest it should lie, as it were, naked and despoiled!' thus also (he thinks):--that is the reason why he covers it over.