Śatapatha Brāhmaṇa ("of a hundred paths") 7.3.2.3

7.3.2.3

yadveva prokṣati | havirvā etattadetadabhighārayati yadvai havirabhyaktaṃ yadabhighāritaṃ tajjuṣṭaṃ tanmedhyamājyenājyena hi havirabhighārayanti tūṣṇīṃ tūṣṇīṃ hi havirabhighārayanti darbhaiste hi śuddhā medhyā agrairagraṃ hi devānām

And, again, why he sprinkles,--this (layer of bricks) is sacrificial food, and as such he bastes it; for whatever sacrificial food is buttered, and basted, that is palatable and sacrificially clean. With ghee (he bastes it), for sacrificial food is basted with ghee; silently (he does so), for silently sacrificial food is basted;--by means of stalks of Kusa grass, for these are pure, and sacrificially clean;--by means of the tops, for the top is sacred to the gods.