Natyashastra
इत्योष्ठलक्षणं प्रोक्तं विनियोगं निबोधत । असूयावेदनावज्ञाभयादिषु विवर्तनम् ॥ १४५॥
These are the gestures of the lower lips; now listen about their uses. Vivartana (narrowing)—in envy, pain, contempt, laziness and the like.
english translation
ityoSThalakSaNaM proktaM viniyogaM nibodhata । asUyAvedanAvajJAbhayAdiSu vivartanam ॥ 145॥
hk transliteration by Sanscript