Śatapatha Brāhmaṇa ("of a hundred paths") 14.2.2.51

14.2.2.51

tadāhuḥ yatprayājānuyājā anyatra bhavantyatha kasmādatra na bhavantīti prāṇā vai prayājānuyājāḥ prāṇā avakāśāḥ prāṇāḥ śākala netprāṇaiḥ prāṇānabhyārohayāṇīti

And, again, they say, 'Seeing that elsewhere there are fore-offerings and after-offerings, wherefore are there not any on this occasion?' Well, the fore-offerings and after-offerings being the vital airs, and so also the Avakâsas, and the pieces of wood, (it is so) lest he should cause the vital airs to be overtopped by vital airs.