Shiva Purana
नास्तिकाय न वक्तव्यमश्रद्धाय शठाय च ॥ अभक्ताय महेशस्य तथा धर्मध्वजाय च ॥ ४४ ॥
It shall not be mentioned to an atheist nor to one lacking in faith nor to a stubborn rogue nor to one who is not a devotee of Śiva nor to a religious hypocrite.
english translation
nAstikAya na vaktavyamazraddhAya zaThAya ca ॥ abhaktAya mahezasya tathA dharmadhvajAya ca ॥ 44 ॥
hk transliteration by Sanscript