Shatapatha Brahmana 14.1.1.27

14.1.1.27

samvatsaravāsine'nubrūyāt eṣa vai samvatsaro ya eṣa tapatyeṣa u pravargyastadetamevaitatprīṇāti tasmātsamvatsaravāsine'nubrūyāt

He may teach it to one dwelling with him (as a pupil) for a year; for the year is he that shines yonder, and the Pravargya also is that (sun): it is him he thereby gratifies, and therefore he may teach it to one dwelling with him for a year.