Mahabharata 12.324.2

भीष्म उवाच · bhīṣma uvāca

अत्राप्युदाहरन्तीममितिहासं पुरातनम्ऋषीणां चैव संवादं त्रिदशानां च भारत

atrāpyudāharantīmamitihāsaṃ purātanamṛṣīṇāṃ caiva saṃvādaṃ tridaśānāṃ ca bhārata

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