Śatapatha Brāhmaṇa ("of a hundred paths") 14.1.3.2

14.1.3.2

athādhvaryuḥ prokṣaṇīrādāyopottiṣṭhannāha brahmanpracariṣyāmo hotarabhiṣṭuhīti brahmā vai yajñasya dakṣiṇata āste'bhigoptā tamevaitadāhāpramatta āssva yajñasya śiraḥ pratidhāsyāma iti hotarabhiṣṭuhīti yajño vai hotā tamevaitadāha yajñasya śiraḥ pratidhehīti pratipadyate hotā

Then the Adhvaryu takes the (lustral) sprinkling water, and, stepping up, says, 'Brahman, we shall proceed: Hotri, sing praises!' for the Brahman is seated on the right (south) side as the guardian of the sacrifice: to him he thus says, 'Sit thou undistracted: we are about to restore the head of the Sacrifice;' and 'Hotri, sing praises!' he says, because the Hotri is the sacrifice: he thus thereby says to him, 'Restore the head of the sacrifice!' and accordingly the Hotri begins to recite--