Shatapatha Brahmana 11.5.4.17

11.5.4.17

tadu vā āhuḥ kāmameva careddvayyo vā imāḥ prajā daivyaścaiva manuṣyaśca tā vā imā manuṣyaḥ prajāḥ prajananātprajāyante candāṃsi vai daivyaḥ prajāstāni mukhato janayate tata etaṃ janayate tasmādu kāmameva caret

And concerning this they also say, 'He may nevertheless do so, if he chooses; for these creatures are of two kinds, divine and human,--these human creatures are born from the womb, and the divine creatures, being the metres (verses of scripture), are born from the month: it is therefrom he (the teacher) produces him, and therefore he may do so (have intercourse) if he chooses.'