Shatapatha Brahmana 11.2.7.1

11.2.7.1

saṃvatsaro yajñaḥ sa yo ha vai saṃvatsaro yajña iti vedānte haivāsya saṃvatsarasyeṣṭam bhavatyatho yatkiṃ ca saṃvatsare kriyate sarvaṃ haivāsya tadāptamavaruddhamabhijitam bhavati

The Sacrifice is the Year; and, verily, sacrifice is offered at the end of the year of him whoso knows that the sacrifice is the year; and all that is done in the year comes to be gained, secured, and won for him.