Shatapatha Brahmana 13.2.6.9

13.2.6.9

apa vā etasmāt tejo brahmavarcasaṃ krāmati yo'śvamedhena yajate hotā ca brahmā ca brahmodyaṃ vadata āgneyo vai hotā bārhaspatyo brahmā brahma bṛhaspatistejaścaivāsminbrahmavarcasaṃ ca samīcī dhatto yūpamabhito vadato yajamāno vai yūpo yajamānamevaitattejasā ca brahmavarcasena cobhayataḥ paridhattaḥ

Verily, fiery spirit and spiritual lustre pass away from him who performs the Asvamedha. The Hotri and the Brahman engage in a Brahmodya (theological discussion); for the Hotri relates to Agni, and the Brahman (priest) to Brihaspati, Brihaspati being the Brahman (n.): fiery spirit and spiritual lustre he thus bestows together on him. With the (central) sacrificial stake between them, they discourse together; for the stake is the Sacrificer: he thus encompasses the Sacrificer on both sides with fiery spirit and spiritual lustre.