The Compendium of Caraka 3.8.14

3.8.14

na caiva hyasti sutaramāyurvedasya pāraṃ, tasmādapramattaḥ śaśvadabhiyogamasmin gacchet, *etacca kāryam. evaṃbhūyaśca vṛttasauṣṭhavamanasūyatā parebhyo 'apyāgamayitavyaṃ, kṛtsno hi loko buddhimatāmācāryaḥ śatruścābuddhimatām, ataścābhisamīkṣya buddhimatā 'amitrasyāpi dhanyaṃ yaśasyamāyuṣyaṃ pauṣṭikaṃ *laukyamabhyupadiśato vacaḥ śrotavyamanuvidhātavyaṃ ceti/

'For there is indeed no absolute end to Āyurveda; therefore, unremitting, one should constantly pursue application to it. And this must be done: further excellence of conduct should be acquired without jealousy even from others. For the entire world is a teacher to the wise, and an enemy to the unwise. Hence, considering this, the wise person should listen to and comply with words even of an enemy that are auspicious, fame-bringing, lifespan-prolonging, nourishing, and practical as he instructs.'