Śatapatha Brāhmaṇa ("of a hundred paths") 6.2.2.12

6.2.2.12

yadveva vāyavyaḥ paśurbhavati | prājāpatyaḥ paśupuroḍāśaḥ prajāpatiṃ vistrastaṃ yatra devāḥ samaskurvantsa yo 'smātprāṇo madhyata udakrāmattamasminnetena paśunādadhurathāsyaitena puroḍāśenātmānaṃ samaskurvantsa yatprājāpatyo bhavati prajāpatirhyātmā dvādaśakapālo dvādaśa māsāḥ saṃvatsaraḥ saṃvatsaraḥ prajāpatiḥ kadvatyau yājyānuvākye ko hi prajāpatiḥ

And, again, why the victim belongs to Vâyu, and the animal cake to Pragâpati;--when the gods restored the relaxed Pragâpati, they, by means of this victim, put into him that out-breathing which had gone out of him; and by means of this cake they restored that body (trunk) of his. And as to why it belongs to Pragâpati, it is because the body (self) is Pragâpati; and (why it is) one on twelve potsherds,--twelve months are a year, and Pragâpati is the year. One of the offering prayers and one of the invitatory prayers contain (the word) 'ka,' for Pragâpati is Ka.