Śatapatha Brāhmaṇa ("of a hundred paths") 1.9.3.2

1.9.3.2

sa eṣa devayāno vā pitṛyāṇo vā panthāḥ | tadubhayato 'gniśikhe samoṣantyau tiṣṭhataḥ prati tamoṣato yaḥ pratyuṣyo 'tyu taṃ sṛjate yo 'tisṛṃjyaḥ śāntirāpastadetamevaitatpanthānaṃ śamayati 1.9.3[[.]]3 pūrṇaṃ ninayati sarvaṃ vai pūrṇaṃ sarveṇaivainametacamayati saṃtatamavyavacinnaṃ ninayati saṃtatenaivainametadavyavacinnena ṣamayati

That same path leads either to the gods or to the fathers. On both sides two flames are ever burning: they scorch him who deserves to be scorched, and allow him to pass who deserves to pass. Now, water is (a means of) lustration: hence he thereby lustrates that path.