Śatapatha Brāhmaṇa ("of a hundred paths") 1.5.3.9

1.5.3.9

sa vai samidho yajati | vasanto vai samidvasantameva taddevā avṛñjata vasantātsapatnānantarāyanvasantamevaiṣa etadvṛṅkte vasantātsapatnānantareti tasmātsamidho yajati

He (the Hotri) now pronounces the offering-prayer (yâgyâ) to the Samidhs. The samidh (kindler), doubtless, is the spring. The gods, at that time, appropriated the spring, and deprived their rivals of the spring; and now this one (the sacrificer) also appropriates the spring, and deprives his rivals of the spring: this is the reason why he pronounces the offering-prayer to the Samidhs.