Śatapatha Brāhmaṇa ("of a hundred paths") 13.6.2.16

13.6.2.16

udayanīyāyāṃ saṃsthitāyām ekādaśa vaśā anūbandhyā ālabhate maitrāvaruṇīrvaiśvadevīrbārhaspatyā etāsāṃ dev atānāmāptyai tadyadbārhaspatyā antyā bhavanti brahma vai bṛhaspatistadu brahmaṇyevāntataḥ pratitiṣṭhati

The Udayanîyâ (concluding oblation) having been completed, he seizes eleven barren cows, sacred to Mitra-Varuna, the Visve Devâh, and Brihaspati, with the view of winning these deities. And as to those of Brihaspati being last,--Brihaspati truly is the Brahman (n.), and thus he finally establishes himself in the Brahman.