Shatapatha Brahmana 6.5.3.5

6.5.3.5

athokhāṃ karoti | ātmānaṃ tatkarotyatha viśvajyotiṣaḥ karoti prajā vai viśvajyotiḥ prajā hyeva viśvaṃ jyotiḥ prajananamevaitatkaroti tā etasyā eva mṛdaḥ karotyātmanastatprajāṃ nirmimīte yajamānaḥ karoti yajamānastadātmanaḥ prajāṃ karotyanantarhitāḥ karotya nantarhitāṃ tadātmanaḥ prajāṃ karotyuttarāḥ karotyuttarāṃ tadātmanaḥ prajāṃ karoti tryālikhitā bhavanti trivṛddhi prajātiḥ pitā mātā putro 'tho garbha ulbaṃ jarāyu

He makes the fire-pan: thereby he makes (Agni's) self. He then makes the 'all-light' (bricks),--the 'all-light' (brick) is offspring, for offspring indeed is all the light: he thus causes generation to take place. He makes them of the same clay (as the fire-pan): he thus produces offspring from the self. The Sacrificer makes them: the Sacrificer thus produces offspring from his own self. He makes them without interruption: he thus produces uninterrupted offspring from his own self. He makes them subsequently (to the fire-pan): he thus produces the offspring subsequently to his own self. They are marked with three lines, for generation is threefold, father, mother, and son; or, the embryo, and the inner and outer membrane.