Shatapatha Brahmana 1.4.1.21

1.4.1.21

tadu ghṛtācyeti | devāñjigāti sumnayuriti yajamāno vai sumnayuḥ sa hi devāñjigīṣati sa hi devāñjighāṃsati tasmādāha devāñjigāti sumnayuriti saiṣāgneyī satyaniruktā sarvaṃ vā aniruktaṃ sarveṇaivaitatpratipadyate

Now that (word) is ghritâkyâ, 'with the buttered (spoon).'--'He nears the gods, wishful of bliss.' Wishful of bliss, truly, is the sacrificer, since he wishes to approach the gods, to go to the gods: therefore he says, 'he nears the gods, wishful of bliss.' This (verse), which is addressed to Agni, is undefined (vague); and undefined, doubtless, is the 'All;' he thus commences (this holy work) with the All.