Shatapatha Brahmana 11.5.4.1

11.5.4.1

brahmacaryamāgāmityāha brahmaṇa evaitadātmānaṃ nivedayati brahmacāryasānītyāha brahmaṇa evaitadātmānam paridadātyathainamāha ko nāmāsīti prajāpatirvai kaḥ prājāpatyamevainaṃ tatkṛtvopanayate

He says, 'I have come for Brahmakarya:' he thereby reports himself to the Brahman. He says, 'Let me be a Brahmakârin (student):' he thereby makes himself over to the Brahman. He (the teacher) then says, 'What (ka) is thy name?'--now Ka is Pragâpati: he thus initiates him after making him one belonging to Pragâpati.