Mahabharata 12.128.30

परस्पराभिसंरक्षा राज्ञा राष्ट्रेण चापदिनित्यमेवेह कर्तव्या एष धर्मः सनातनः

parasparābhisaṃrakṣā rājñā rāṣṭreṇa cāpadinityameveha kartavyā eṣa dharmaḥ sanātanaḥ

Our plain-language meaning of this verse is waiting for scholar review.