Natyashastra
उपस्थितस्मृतिश्चैव गात्रं सर्वं विधाय च । अचञ्चलमनाश्चैव यथावल्लिङ्गमाश्रितः ॥ ८१॥
Having kept the entire body steady and firm, with immobile limbs, and maintaining the prescribed posture firmly as required.
english translation
upasthitasmRtizcaiva gAtraM sarvaM vidhAya ca । acaJcalamanAzcaiva yathAvalliGgamAzritaH ॥ 81॥
hk transliteration by Sanscript