Śatapatha Brāhmaṇa ("of a hundred paths") 14.1.2.2

14.1.2.2

kṛṣṇājinaṃ sambharati yajño vai kṛṣṇajinaṃ yajña evainametatsambharati lomataścandāṃsi vai lomāni candaḥsvevainametatsambharatyuttarata udīcī hi manuṣyāṇāṃ dikprācīnagrīve taddhi devatrā

He gets ready a black antelope-skin,--for the black antelope-skin is the sacrifice: it is at the sacrifice he thus prepares (the pot);--with its hairy side (upwards),--for the hairs are the metres: on the metres he thus prepares it;--(spread out) on the left (north) side,--for the north is the quarter of men;--on (the skin) with its neck-part to the east, for that (tends) towards the gods.