Mahabharata 15.6.20

ग्लायते मे मनो हीदं मुखं च परिशुष्यतिवयसा च प्रकृष्टेन वाग्व्यायामेन चैव हि

glāyate me mano hīdaṃ mukhaṃ ca pariśuṣyativayasā ca prakṛṣṭena vāgvyāyāmena caiva hi

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