Śatapatha Brāhmaṇa ("of a hundred paths") 7.2.3.5

7.2.3.5

yadvevainamabhijuhoti | etadvai yatraitam prāṇā ṛṣayo 'gre 'gniṃ samaskurvaṃstadasminnetam purastādbhāgamakurvata tasmātpurastādbhāgāstadyadabhijuhoti ya evāsmiṃste prāṇā ṛṣayaḥ purastādbhāgamakurvata tānevaitatprīṇātyājyena pañcagṛhītena tasyokto bandhuḥ

And, again, why he offers thereon;--when in the beginning the Rishis, the vital airs, put together this Agni, they gained for themselves that fore-share in him: hence they are the fore-sharers. Thus when he offers on (the grass-bush) he thereby gratifies those Rishis, the vital airs, who gained for themselves the fore-share in him (Agni). With fivefold-taken ghee (he offers): the significance of this has been explained.