Śatapatha Brāhmaṇa ("of a hundred paths") 7.3.1.11

7.3.1.11

tadāhuḥ | yadyoniḥ pariśrito retaḥ sikatā atha pūrvāḥ pariśridbhyo gārhapatye sikatā nivapati kathamasyaitadreto 'parāsiktam parigṛhītam bhavatītyulbaṃ vā ūṣāstadyadūṣānpūrvānnivapatyeteno hāsyaitadulbena reto 'parāsiktam parigṛhītam bhavatyathāhavanīye pariśrito 'bhimantrayate tasyokto bandhuratha sikatā nivapati reto vai sikatā etayo asyaitadyonyā reto 'parāsiktam parigṛhītam bhavati

As to this they say, 'If the enclosing-stones are the womb, and the sand is seed, and the sand is strown on the Gârhapatya before (the setting up of) the enclosing-stones, how, then, is that seed of his not shed aside, (but) is received (by the womb)?' Well, the saline soil is the amnion, and inasmuch as he strews first the saline soil, that seed of his is not shed aside, but is received by that amnion. He now addresses the enclosing-stones on the Âhavanîya: the meaning of this has been explained. He then scatters sand: sand being seed, that seed of his is not shed aside, but is received also by that womb.