Vitthatasutta 3.2

3.2

Idha, bhikkhave, ariyasāvako hirīmā hoti, hirīyati kāyaduccaritena vacīduccaritena manoduccaritena, hirīyati pāpakānaṃ akusalānaṃ dhammānaṃ samāpattiyā.

It’s when a noble disciple has a conscience. They’re conscientious about bad conduct by way of body, speech, and mind, and conscientious about having any bad, unskillful qualities.