Shatapatha Brahmana 13.5.4.25

13.5.4.25

udayanīyāyāṃ samsthitāyām ekaviṃśatim vaśā anūbandhyā ālabhate maitrāvaruṇīrvaiśvadevīrbārhaspatyā etāsāṃ devatānāmāptyai tadyadbārhaspatyāntyā bhavanti brahma vai bṛhaspatistadu brahmaṇyevāntataḥ pratitiṣṭhati

When the Udayanîyâ (completing offering) is finished, he seizes twenty-one barren cows, sacred to Mitra-Varuna, the Visve Devâh, and Brihaspati, with the view of his gaining those deities. And the reason why those sacred to Brihaspati come last is that Brihaspati is the Brahman (n.), and he thus establishes himself finally in the Brahman.