Mahabharata 13.44.2

भीष्म उवाच · bhīṣma uvāca

अयं हि सर्वधर्माणां धर्मश्चिन्त्यतमो मतःकीदृशाय प्रदेया स्यात्कन्येति वसुधाधिप

ayaṃ hi sarvadharmāṇāṃ dharmaścintyatamo mataḥkīdṛśāya pradeyā syātkanyeti vasudhādhipa

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