Since the holy spirit has God as its Source, saying things against his spirit is the same as speaking against Jehovah.
وَبِمَا أَنَّ ٱللهَ هُوَ مَصْدَرُ ٱلرُّوحِ ٱلْقُدُسِ ،‏ فَٱلتَّكَلُّمُ ضِدَّ رُوحِهِ هُوَ بِمَثَابَةِ ٱلتَّكَلُّمِ ضِدَّ يَهْوَه .‏