Yuga-Vibhāga and Kāla-Pramāṇa
Measures of Time and the Four Yugas
प्रजानां रञ्जनाच्चैव राजानस्ते ऽभवन्नृपाः / प्रच्छन्न पापास्तैर्ये च न शक्यास्तु नराधिपैः
prajānāṃ rañjanāccaiva rājānaste 'bhavannṛpāḥ / pracchanna pāpāstairye ca na śakyāstu narādhipaiḥ
Because they delighted the people, those kings came to be called nṛpas; and they restrained even hidden sins that other rulers could not curb.