Śatapatha Brāhmaṇa ("of a hundred paths") 11.5.2.8

11.5.2.8

teṣāṃ vai caturṣvagnim manthanti tasmāccaturbhiraṅgairāyute dvayoḥ praṇayanti tasmāddvābhyāmetyevamu ha prajāpatiścāturmāsyairātmānaṃ vidadhe tatho evaivaṃvidyajamānaścāturmāsyairātmānaṃ vidhatte

At all four of them they churn out the fire, whence (the draught animal) pulls with all four limbs. At two of them they lead (the fire) forward, whence it (the animal) walks on two (feet at a time). Thus, then, Pragâpati fashioned for himself a body by means of the Seasonal sacrifices; and in like manner does the Sacrificer who knows this fashion for himself a (divine) body by means of the Seasonal sacrifices.