Majjhima Nikaya 4:76
SUJATOYañhissa, bhikkhave, manindriyasaṁvaraṁ asaṁvutassa viharato uppajjeyyuṁ āsavā vighātapariḷāhā, manindriyasaṁvaraṁ saṁvutassa viharato evaṁsa te āsavā vighātapariḷāhā na honti.
For the distressing and feverish defilements that might arise in someone who lives without restraint of the mind faculty do not arise when there is such restraint.