Mahabharata 12.79.9

अत्र ते वर्तयिष्यामि यथा धर्मः पुरातनःव्यवहारप्रवृत्तानां तन्निबोध युधिष्ठिर

atra te vartayiṣyāmi yathā dharmaḥ purātanaḥvyavahārapravṛttānāṃ tannibodha yudhiṣṭhira

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