Mahabharata 13.84.41

आवृत्तजिह्वस्य सतो वाक्यं कान्तं भविष्यतिबालस्येव प्रवृद्धस्य कलमव्यक्तमद्भुतम्

āvṛttajihvasya sato vākyaṃ kāntaṃ bhaviṣyatibālasyeva pravṛddhasya kalamavyaktamadbhutam

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