Śatapatha Brāhmaṇa ("of a hundred paths") 4.1.4.10

4.1.4.10

sa śrīṇāti | rāyā vayaṃ sasavāṃso madema havyena devā yavasena gāvaḥ tāṃ dhenum mitrāvaruṇā yuvaṃ no viśvāhā dhattamanapasphurantīmeṣa te yonirṛtāyubhyāṃ tveti sādayati sa yadāhartāyubhyāṃ tveti brahma vā ṛtam brahma hi mitro brahmo hyṛtaṃ varuṇa evāyuḥ saṃvatsaro hi varuṇaḥ saṃvatsara āyustasmādāhaiṣa te yoni ṛtāyubhyāṃ tveti

He mixes it with (Vâg. S. VII, 10; Rig-veda IV, 42, 10), 'May we delight in the wealth we have gained, the gods in the offering, the kine in pasture! that unfailing milch cow, O Mitra and Varuna, grant ye unto us day by day!'--with 'This is thy womb: thee for truth and life!' he deposits it. Now as to why he says, 'Thee for truth and life,'--the truth is Mitra, since Mitra is the Brahman, and the truth is the Brahman (sacerdotium or sacred writ);--and life is Varuna, since Varuna is the year, and life is the year: therefore he says, 'This is thy womb: thee for truth and life!'