Śatapatha Brāhmaṇa ("of a hundred paths") 14.2.2.27

14.2.2.27

atha pinvamānamanumantrayate iṣe pinvasveti vṛṣṭyai tadāha yadāheṣe pinvasvetyūrje pinvasveti yo vṛṣṭādūrgraso jāyate tasmai tadāha brahmaṇe pinvasveti tadbrahmaṇa āha kṣatrāya pinvasveti tatkṣatrāyāha dyāvāpṛthivībhyām pinvasveti tadābhyāṃ dyāvāpṛthivībhyāmāha yayoridaṃ sarvamadhi

The rising (milk) he then consecrates by the anumantrana, 'For freshness swell thou!' --whereby he means to say, 'For rain...;'--'for vigour swell thou!'--he thereby means the vigour, the life-sap, which results from the rain;--'for the Brahman swell thou!'---he thereby means the priesthood;--'for the Kshatra swell thou!'--he thereby means the nobility;--'for Heaven and Earth swell thou!'--he thereby means these two, the heaven and the earth, within which everything here is contained.