Shatapatha Brahmana 11.1.5.6

11.1.5.6

sa yadagnaye pathikṛte nirvapati agnirvai pathaḥ kartā sa yasmādevādo yajamāno yajñapathādeti tamenamagniḥ panthānamāpādayati

Now as to why he prepares (an oblation) for Agni Pathikrit,--it is that Agni, being the maker of the path, leads the Sacrificer (back) to the path of sacrifice, from which he now departs.