Mark 3:29

but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation"--

Surrounding context

3:28 "Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter;

3:29 but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation"--

3:30 because they said, "He has an unclean spirit."

Translation and sources