Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.1.11

2.5.1.11

atha sārasvataścarurbhavati | pauṣṇaścaruryoṣā vai sarasvatī vṛṣā pūṣā tatpunarmithunam prajananametasmādvā ubhayato mithunātprajananātprajāpatiḥ prajāḥ sasṛja itaścordhvā itaścāvācīstatho evaiṣa etasmādubhayata eva mithunātprajananātprajāḥ sṛjata itaścordhvā itaścāvācīstasmādvā etāni pañca havīṃṣi bhavanti

Then follows a potful of boiled rice for Sarasvatî; and another for Pûshan. Sarasvatî doubtless is a woman, and Pûshan is a man: thus there is again a productive union. Through that twofold productive union Pragâpati created the living beings,-- through the one (he created) the upright, and through the other those looking to the ground. This is why there are these five oblations.