Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.1.4

2.1.1.4

yoṣā vā āpaḥ | vṛṣāgnirmithunenaivainametatprajananena samardhayatyadbhirvā idaṃ sarvamāptamadbhirevainametadāptvādhatte tasmādapaḥ sambharati

Water (ap, fem.), moreover, is female, and fire (agni, masc.) is male; so that he thereby supplies the latter with a productive mate. And since all this (universe) is pervaded (or obtained, âpta) by water, he sets up the fire, after he has obtained it by means of water. This is why he brings water.