Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.2.5

2.5.2.5

tadvai dve vedī dvāvagnī bhavataḥ | tadyaddve vedī dvāvagnī bhavatastadubhayata evaitadvaruṇapāśātprajāḥ pramuñcatītaścordhvā itaścāvācīstasmāddve vedī dvāvagnī bhavataḥ

At this (sacrifice) there are two altars and two fires. The reason why there are two altars and two fires, is that thereby one frees the creatures from Varuna's noose both ways,--on the one side (he frees) the upright, and on the other those looking to the ground: this is why there are two altars and two fires.