Natyashastra
करौ वक्षसि निक्षिप्य कुब्जीभूतस्तथैव च । दन्तोष्ठस्फुरणं चैव चिबुकस्य प्रकम्पनम् ॥ ६९॥
The hands should be placed on the chest, bent forward as if hunched; the teeth and lips should chatter, and the chin should tremble.
english translation
karau vakSasi nikSipya kubjIbhUtastathaiva ca । dantoSThasphuraNaM caiva cibukasya prakampanam ॥ 69॥
hk transliteration by Sanscript