Mahabharat

siva.sh/mahabharat/virata-parva/4/30

न चातिधैर्येण चरेद गुरुतां हि वरजेत तथा समितं तु मृदुपूर्वेण दर्शयेत परसादजम ।। ४-४-३० ।।

sanskrit

'Nor should one conduct himself with excessive gravity, for that too may appear arrogant. Instead, let him display a gentle smile, showing his goodwill with softness and humility.' ।। 4-4-30 ।।

english translation

na cAtidhairyeNa careda gurutAM hi varajeta tathA samitaM tu mRdupUrveNa darzayeta parasAdajama || 4-4-30 ||

hk transliteration by Sanscript