Natyashastra
नासाग्रसक्ता निमिषा तथाधोभागचारिणी । आकेकरपुटा शान्ते शान्ता दृष्टिर्भवेदसौ ॥ ५४॥
When the gaze is fixed on the tip of the nose, with occasional blinking and a downward movement, and when the eyelids are slightly contracted, such a gaze is called Śāntā (the calm or serene gaze).
english translation
nAsAgrasaktA nimiSA tathAdhobhAgacAriNI । AkekarapuTA zAnte zAntA dRSTirbhavedasau ॥ 54॥
hk transliteration by Sanscript