Shatapatha Brahmana 9.2.1.13

9.2.1.13

yadvevainaṃ samukṣati | etadvai yatraitam prāṇā ṛṣayo 'gre 'gniṃ samaskurvaṃstadasminnado 'mum purastādbhāgamakurvatādaḥ sajūrabdīyamathāsminnetaṃ saṃcita upariṣṭādbhāgamakurvata tadyatsamukṣati ya evāsmiṃste prāṇā ṛṣayaḥ sacita upariṣṭādbhāgamakurvata tānevaitatprīṇāti dadhnā madhunā ghṛtena tasyokto bandhuḥ

And, again, as to why he sprinkles them;--of old, when the Rishis, the vital airs, joined him together, they made that 'sagûrabdîya' (oblation) his special fore-share, and, when he had been built up, they made this (sprinkling) his after-share: thus, in sprinkling him, he gratifies those Rishis, the vital airs, who, when he (Agni) had been built up, made this his after-share. With sour curds, honey and ghee (he sprinkles): the significance of this has been explained.