Mahabharata 12.276.2

भीष्म उवाच · bhīṣma uvāca

गुरुपूजा च सततं वृद्धानां पर्युपासनम्श्रवणं चैव विद्यानां कूटस्थं श्रेय उच्यते

gurupūjā ca satataṃ vṛddhānāṃ paryupāsanamśravaṇaṃ caiva vidyānāṃ kūṭasthaṃ śreya ucyate

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