Mahabharata 12.288.2

भीष्म उवाच · bhīṣma uvāca

अत्र ते वर्तयिष्येऽहमितिहासं पुरातनम्साध्यानामिह संवादं हंसस्य च युधिष्ठिर

atra te vartayiṣye'hamitihāsaṃ purātanamsādhyānāmiha saṃvādaṃ haṃsasya ca yudhiṣṭhira

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