Śatapatha Brāhmaṇa ("of a hundred paths") 1.5.3.3

1.5.3.3

tato devāḥ | arcantaḥ śrāmyantaścerurasta etānprayājāndadṛśustairayajanta tairṛtūntsaṃvatsaram prājayannṛtubhyaḥ saṃvatsarātsapatnānantarāyaṃstasmātprajayāḥ prajayā ha vai nāmaitadyatprayājā iti tatho evaiṣa etairṛtūntsaṃvatsaram prayajatyṛtubhyaḥ saṃvatsarātsapatnānantareti tasmātprayājairyajate

Then the gods went on praising and toiling. They saw these fore-offerings and worshipped with them. By means of them they gained (pra-gi) the seasons, the year; they deprived their rivals of the seasons, of the year: hence (the fore-offerings are) victories (pragaya), for, assuredly, pragaya is the very same term as prayâga (fore-offering). And in the same way this one (the sacrificer) wins by means of them the seasons, the year; deprives his rivals of the seasons, of the year. This is the reason why he performs the fore-offerings.