Valmiki Ramayana Kishkindha Kanda Sarga 18 Shloka 35

अन्यैरपि by others also, कृतम् committed, पापम् vicious deeds, प्रमत्तैः by those not watchful, वसुधाधिपैः by the kings of the earth, प्रायश्चित्तम् atonement, कुर्वन्ति was done, तेन by that, तत् that, रजः taint, शाम्यते is removed.

'Vicious deeds have been committed by others when the kings were not watchful. Kings punish such sinners when they are vigilant. Otherwise they have to atone for their negligence.