Śatapatha Brāhmaṇa ("of a hundred paths") 3.6.2.5

3.6.2.5

sā yatsuparṇyuvāca | asya salilasya pāra iti vedirvai salilaṃ vedimeva sā taduvācāśvaḥ śveta sthāṇau sevata ityagnirvā aśvaḥ śveto yūpa sthāṇuratha yatkadrūruvāca tasya vālo nyaṣañji tamamuṃ vāto dhūnoti tamaham paśyāmīti raśanā haiva sā

Now when Suparnî said, 'On yonder shore of this ocean,' the ocean, forsooth, is the altar, she thereby meant the altar; 'there stands a white horse at a post,' the white horse, forsooth, is Agni, and the post means the sacrificial stake. And when Kadrû said, 'Its tail was just now hanging down; there, now the wind tosses it, that I see;' this is nothing else than the rope.