Śatapatha Brāhmaṇa ("of a hundred paths") 4.1.1.3

4.1.1.3

tam bahiṣpavitrādgṛhṇāti | parāñcamevāsminnetatprāṇaṃ dadhāti so 'syāyam parāṅeva prāṇo nirardati tamaṃśubhiḥ pāvayati pūto 'saditi ṣaḍbhiḥ pāvayati ṣaḍvā ṛtava ṛtubhirevainametatpāvayati

This (graha) he draws without a strainer: whereby he puts the out-breathing into him as one tending away from him, and thus this forward-tending out-breathing of his streams forth from him. He purifies it with sprigs of Soma, thinking 'it shall be pure.' He purifies it with six (sprigs), for there are six seasons: it is by means of the seasons that he thus purifies it.