Śatapatha Brāhmaṇa ("of a hundred paths") 8.2.1.11

8.2.1.11

yadvevaitā āśvinīrupadadhāti | prajāpatiṃ visrastaṃ devatā ādāya vyudakrāmaṃstasya yadūrdhvam pratiṣṭhāyā avācīnam madhyāttadasyāśvināvādāyotkramyātiṣṭhatām

Now as to why he lays down these Âsvinî (bricks). When Pragâpati had become relaxed (disjointed), the deities took him and went away in different directions. Now what part of him there was above the feet and below the waist, that part of him the two Asvins took and kept going away from him.