It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The most severely punished of the people of Hell on the Day of Resurrection will be one who killed a prophet or whom a prophet killed, and an unjust ruler, and these image-makers (will also be among those severely punished)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10469