Mahabharata 5.165.15
बलज्येष्ठं स्मृतं क्षत्रं मन्त्रज्येष्ठा द्विजातयःधनज्येष्ठाः स्मृता वैश्याः शूद्रास्तु वयसाधिकाः
balajyeṣṭhaṃ smṛtaṃ kṣatraṃ mantrajyeṣṭhā dvijātayaḥdhanajyeṣṭhāḥ smṛtā vaiśyāḥ śūdrāstu vayasādhikāḥ
Our plain-language meaning of this verse is waiting for scholar review.
Open in the book