Śatapatha Brāhmaṇa ("of a hundred paths") 3.9.2.15

3.9.2.15

sa uttareṇa niṣkrāmati | tā uttarāyāṃ śroṇau sādayati mitrāvaruṇayorbhāgadheyī stheti naivaṃ sādayedatiriktametannaivaṃ sampatsampadyata indrāgnyorbhāgadheyī sthetyeva brūyāttadevānatiriktaṃ tathā sampatsampadyate

He walks out (of the hall by the east door), along the north side (of the altar), and puts down (the water) on the north hip (of the high altar), with, 'Ye are Mitra and Varuna's share!' Let him not put it down in this way that is redundant, and no fitting conclusion is thus attained. Let him rather (here also) say, 'Ye are Indra and Agni's share!' only thus there is nothing redundant, and so a fitting conclusion is obtained.