Shiva Purana
मानसं च तथा पापं तादृशं नाशयेद्द्विजाः । मानसं वज्रलेपं तु कल्पकल्पानुगं तथा ३८ ।
O brahmins, the mental sin is adamantine in sticking to the sinner and it continues for many Kalpas.
english translation
mAnasaM ca tathA pApaM tAdRzaM nAzayeddvijAH । mAnasaM vajralepaM tu kalpakalpAnugaM tathA 38 ।
hk transliteration by Sanscript