Śatapatha Brāhmaṇa ("of a hundred paths") 5.5.2.5

5.5.2.5

taddha smaitatpurā kurupañcālā āhuḥ | ṛtavo vā asmānyuktā vahantyṛtūnvā prayuktānanucarāma iti yadeṣāṃ rājāno rājasūyayājina āsustaddha sma tadabhyāhuḥ

Now as to this the Kurupañkâlas used formerly to say, 'It is the seasons that, being yoked, draw us, and we follow the seasons thus yoked.' It was because their kings were performers of the Râgasûya that they spake thus.