Manusmriti
न तेन वृद्धो भवति येनास्य पलितं शिरः । यो वै युवाऽप्यधीयानस्तं देवाः स्थविरं विदुः ॥ १५६ ॥
A man is not therefore (considered) venerable because his head is gray; him who, though young, has learned the Veda, the gods consider to be venerable.
english translation
na tena vRddho bhavati yenAsya palitaM ziraH । yo vai yuvA'pyadhIyAnastaM devAH sthaviraM viduH ॥ 156 ॥
hk transliteration by Sanscript