Shatapatha Brahmana 1.4.1.35

1.4.1.35

tadu haike 'nvāhuḥ | hotā yo viśvavedasa iti nedaramityātmāna bravāṇīti tadu tathā na brūyānmānuṣaṃ ha te yajñe kurvanti vyṛddhaṃ vai tadyajñasya yanmānuṣaṃ nedvyṛddham yajñe karavāṇīti tasmādyathaivarcānūktamevānubrūyāddhotāraṃ viśvavedasamityevāsya yajñasya sukratumityeṣa hiyajñasyasukraturyadagnistasmādāhāsya yajñasya sukratumiti seyaṃ devānupāvavarta tato devā abhavanparāsurā bhavati ha vā ātmanā parāsya sapatnā bhavanti yasyaivaṃ viduṣa etāmanvāhuḥ

Here now some people recite, 'He who is the Hotri of the all-knowing;' lest (in saying 'for Hotri, the all-knowing, him') one should say to oneself 'enough (i.e. have done)!' This, however, he should not do; for by (doing) so they do at the sacrifice what is human; and what is human, is inauspicious at a sacrifice. Therefore, lest he should do what is inauspicious at the sacrifice, he should recite, just as it is recited by the Rik, 'for Hotri, the all-knowing, him!' [He continues], 'Performing well this sacrifice!' for he, Agni, is indeed a good performer of the sacrifice: for this reason he says, 'performing well this sacrifice.' She (gâyatrî, or the earth) sided with the gods, and the gods thereupon were victorious and the Asuras were defeated: and verily he for whom, knowing this, they recite this (verse), is himself victorious and his adversaries are defeated.