Shatapatha Brahmana 8.5.1.9

8.5.1.9

sā yā purastādagniḥ sā | yā paścādagniḥ sāgninaiva tatpurastātpāpmānamapāhatāgninā paścāttathaivaitadyajamāno 'gninaiva purastātpāpmānamapahate 'gninā paścāt

That which is (placed) in front is Agni, and that behind is Agni: with Agni he (Pragâpati) then drove away evil both in front and in the rear; and in like manner now does the Sacrificer with Agni drive away evil both in front and in the rear.