Valmiki Ramayana Yuddha Kanda Sarga 12 Shloka 30

दशानन: Ravana, यः whosoever, नृपः is the king, न्यायेन: justifiably, निश्चितार्थमतिः having sense of determination, राजकार्याणि: princely duties, करोति: does, सः he, पश्चात् later, नसन्तप्यते: will not regret.

"O Ravana Whoever is the king, having a sense of determination, thinks justifiably and carries out princely duties will not regret."