Shatapatha Brahmana 11.6.2.10

11.6.2.10

te striyamāviśataḥ tasyā upasthamevāhavanīyaṃ kurvāte dhārakāṃ samidhaṃ dhārakā ha vai nāmaiṣaitayā ha vai prajāpatiḥ prajā dhārayāṃ cakāra reta eva śukrāmāhutiṃ te striyaṃ tarpayataḥ sa ya evaṃ vidvānmithunamupaityagnihotramevāsya hutam bhavati yastataḥ putro jāyate sa lokaḥ pratyutthāyyetadagnihotraṃ yājñavalkya nātaḥ paramastīti hovāca tasmai ha yājñavalkyo varaṃ dadau sa hovāca kāmapraśna eva me tvayi yājñavalkyāsaditi tato brahmā janaka āsa

'They enter woman, and make her lap their offering-fire, her womb the fuel,--for that (womb) is called the bearer, because by it Pragâpati bore creatures,--and the seed their pure libation: they satiate woman; and, verily, for him who, knowing this, approaches his mate, the Agnihotra comes to be offered. The son who is born therefrom is the renascent world: this is the Agnihotra, Yâgñavalkya, there is nothing higher than this.' Thus he spoke; and Yâgñavalkya granted him a boon. He said, 'Let mine be the (privilege of) asking questions of thee when I list, Yâgñavalkya!' Thenceforth Ganaka was a Brahman.