Śatapatha Brāhmaṇa ("of a hundred paths") 1.5.3.11

1.5.3.11

atheḍo yajati | varṣā vā iḍa iti hi varṣā iḍo yadidaṃ kṣudraṃ sarīsṛpaṃ grīṣmahemantābhyāṃ nityaktam bhavati tadvarṣā īḍitamivānnamicamānaṃ carati tasmādvarṣā iḍo varṣā eva taddevā avṛñjata varṣābhyaḥ sapatnānantarāyanvarṣā u evaiṣa etadvṛṅkte varṣābhyaḥ sapatnānantareti tasmādiḍo yajati

He then pronounces the offering-prayer to the Ids. The Ids (praises), doubtless, are the rains; they are the rains, inasmuch as the vile, crawling (vermin) which shrink during the summer and winter, then (in the rainy season) move about in quest of food, as it were, praising (îd) the rains: therefore the Ids are the rains. The gods, at that time, appropriated the rains, and deprived their rivals of the rains; and now this one also appropriates the rains, and deprives his rivals of the rains: this is the reason why he pronounces the offering-prayer to the Ids.