Blasphemy in Islam is impious utterance or action concerning God, Muhammad or anything considered sacred in Islam. The Quran admonishes blasphemy, but does not specify any worldly punishment for blasphemy. The hadiths, which are another source of Sharia, suggest various punishments for blasphemy, which may include death. However, it has been argued that the death penalty applies only to cases where there is treason involved that may seriously harm the Muslim community, especially during times of war. Different traditional schools of jurisprudence prescribe different punishment for blasphemy, depending on whether the blasphemer is Muslim or non-Muslim, a man or a woman. In the modern Muslim world, the laws pertaining to blasphemy vary by county, and some countries prescribe punishments consisting of fines, imprisonment, flogging, hanging, or beheading. In recent years, accusations of blasphemy against Islam have sparked international controversies and played part in incidents of mob violence and assassinations of prominent figures.
In Islamic literature, blasphemy is of many types, and there are many different words for it: sabb (insult) and shatm (abuse, vilification), takdhib or tajdif (denial), iftira (concoction), la`n or la'ana (curse) and ta`n (accuse, defame). In Islamic literature, the term "blasphemy" sometimes also overlaps with kufr ("unbelief"), fisq (depravity), isa'ah (insult), and ridda (apostasy).
There are a number of surah in Qur'an relating to blasphemy, from which Quranic verses 5:33 and 33:57–61 have been most commonly used in Islamic history to justify punishment for blasphemy. For example,