Śatapatha Brāhmaṇa ("of a hundred paths") 1.7.2.26

1.7.2.26

atho itarathāhuḥ ya eva devānāmāsītso 'yavā na hi tamasurā ayuvata yo 'surāṇāṃ sa yavāyuvata hi taṃ devāḥ sabdamahaḥ sagarā rātriryavyā māsāḥ sumekaḥ saṃvatsaraḥ sveko ha vai nāmaitadyatsumeka iti yavā ca hi vā ayavā yavetīvātha yenaiteṣāṃ hotā bhavati tadyāvihotramityācakṣate

But they also say contrariwise:--That which belonged to the gods is (called) ayavan, because the Asuras did not get possession of it; and that which belonged to the Asuras is yavan, because the gods did get possession of it. The day is (called) sabda, the night sagarâ, the months yavya, the year sumeka: sveka ('eminently one'), doubtless, is the same as sumeka. And since the Hotri is concerned with these--to wit, the yavan and the ayavan, which (according to some) is yavan--they call (his office) yâvihotram.