Śatapatha Brāhmaṇa ("of a hundred paths") 2.6.2.4

2.6.2.4

te vai pratipuruṣam | yāvanto gṛhyāḥ syustāvanta ekenātiriktā bhavanti tatpratipuruṣamevaitadekaikena yā asya prajā jātāstā rudriyātpramuñcatyekenātiriktā bhavanti tadyā evāsya prajā ajātāstā rudriyātpramuñcati tasmādekenātiriktā bhavanti

There is one for each individual,--as many as he has descendants,--exceeded by one. (There being) one for each individual, he thereby delivers from Rudra's power the descendants that are born unto him; and there being an additional one, he thereby delivers from Rudra's power the descendants that are not yet born to him: this is why there are (as many cakes as there are descendants) exceeded by one.