Bhagavatapurana 5.14.30

5.14.30

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yadā pākhaṇḍibhir ātma-vañcitais tair uru vañcito brahma-kulaṃ samāvasaṃs teṣāṃ śīlam upanayanādi-śrauta-smārta-karmānuṣṭhā-nena bhagavato yajña-puruṣasyārādhanam eva tad arocayan śūdra-kulaṃ bhajate nigamācāre 'śuddhito yasya mithunī-bhāvaḥ kuṭumba-bharaṇaṃ yathā vānara-jāteḥ //

30. When he is thus greatly deceived by the Pakhandas who have deceived themselves; and, though living in the Brahmin community, yet he feels no liking to their pious character and to their worship of the glorious Lord of sacrifices by observing the duties laid down in Srutis and Smritis such as Upanayana, he resorts to the Sudra community and adopts what is declared sinful in the code of Aryan conduct such as addiction to sexual pleasure and earning bread for his own family as the monkey race does.