The Compendium of Caraka 1.25.34

1.25.34

evaṃvādinaṃ ca bhagavantamātreyamagniveśa uvāca bhagava na tvetadevamupadiṣṭaṃ bhūyiṣṭhakalpāḥ sarvabhiṣajo vijñāsyanti //

And to the blessed Ātreya speaking thus, Agniveśa said: “Blessed one, almost all physicians will not understand it when taught in this manner.”