Charak Samhita
वारिविप्रहताः क्षीणा भीता नकुलनिर्जिताः । वृद्धा बालास्त्वचो मुक्ताः सर्पा मन्दविषाः स्मृताः ॥१६३॥
[Snakes with mild poisonous effect] The snakes which are affected with water, are weak, terrorized, defeated by mongoose, old, of tender age, sloughed are known as having mild poison.
english translation
vAriviprahatAH kSINA bhItA nakulanirjitAH । vRddhA bAlAstvaco muktAH sarpA mandaviSAH smRtAH ॥163॥
hk transliteration by Sanscript