Śatapatha Brāhmaṇa ("of a hundred paths") 1.3.3.8

1.3.3.8

yoṣā vai vediḥ | tāmetaddevāśca paryāsate ye ceme brāhmaṇāḥ śuśruvāṃso 'nūcānāsteṣvevaināmetatparyāsīneṣvanagnāṃ karotyanagnatāyā eva tasmādbarhi stṛṇāti

Now the altar (vedi, fem.) is a woman, and around her sit the gods and those priests who have studied and teach revealed lore; and as they thus sit around her, he makes her not naked: hence it is in order to avoid nudity (on her or the altar's part) that he spreads the barhis.