Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.2.19

2.5.2.19

āsādya havīṃṣyagnim manthati | agnim manthitvānuprahṛtyābhijuhotyathādhvaryurevāhāgnaye samidhyamānāyānubrūhīti tā ubhāvevedhmāvabhyādhatta ubhau samidhau pariśiṃṣṭa ubhau pūrvāvāghārāvāghārayato 'thādhvaryurevāhāgnimagnītsammṛḍḍhītyasammṛṣṭameva bhavati sampreṣitam

Having thus placed the sacrificial dishes, he churns the fire; and having churned it and placed it on (the hearth), he offers thereon, The Adhvaryu in the first place says (to the Hotri), 'Recite to the fire that is being kindled!' Both (the Adhvaryu and the Pratiprasthâtri) then put firewood on (the fire) and both reserve one kindling-stick each; and they both pour out the first libation (âghâra). Thereupon the Adhvaryu says, 'Agnîdh, trim the fire!' Although the summons is given, the trimming does not take place (immediately)