Gopalasutta 6.9

6.9

yatvādhikaraṇamenaṃ manindriyaṃ asaṃvutaṃ viharantaṃ abhijjhādomanassā pāpakā akusalā dhammā anvāssaveyyuṃ, tassa saṃvarāya na paṭipajjati; na rakkhati manindriyaṃ, manindriye saṃvaraṃ nāpajjati.

Since the faculty of the mind is left unrestrained, bad unskillful qualities of covetousness and displeasure become overwhelming. They don’t practice restraint, they don’t protect the faculty of the mind, and they don’t achieve its restraint.