Shatapatha Brahmana 5.5.5.13

5.5.5.13

atho ye dīrghasattramāsīran | saṃvatsaraṃ vā bhūyo vā teṣāṃ hāpyudavasānīya syātsarvaṃ vai teṣāmāptam bhavati sarvaṃ jitaṃ ye dīrghasattramāsate saṃvatsaraṃ vā bhūyo vā sarvameṣā tasmādu ha teṣāmapyudavasānīyā syāt

And also for those who would sit through (perform) a long sacrificial session, for a year or more, let this be the completing offering. For by those who sit through a long sacrificial session, for a year or more, everything is obtained, everything conquered; but this (offering) is everything: let it therefore be for them also the completing offering.