Shatapatha Brahmana 11.1.6.27

11.1.6.27

catasro'vāntaradiśaḥ ta eva catvāraḥ patnīsaṃyājā avāntaradiśo vai devāścaturbhiḥ patnīsaṃyājairajayannavāntaradiśa u evaiṣa etairjayati

And the four Patnîsamyâgas are the four intermediate quarters; and, indeed, it was by the four Patnîsamyâgas that the gods gained the intermediate quarters; and by means of them this (Sacrificer) now gains the intermediate quarters.