Criticism of ḥadīth is the critique of ḥadīth—the genre of canonized Islamic literature made up of attributed reports of the words, actions, and the silent approval of the Islamic prophet Muhammad. The legitimacy of ḥadīth is of considerable importance in mainstream Islam because of Quranic injunctions for Muslims to obey Muhammad (in verses such as 24:54, 3:32), and that "he is an excellent example for anyone who has hope in Allah and the last day" (33:21). Mainstream Islam holds that the Sunnah—teachings and doings of Muhammad—are like the Quran, divine revelation to be obeyed, but the "great bulk" of the rules of Sharia (Islamic law) are derived from ḥadīth rather than the Quran. However, some Muslims reject the authority of the hadiths, viewing them as un-Quranic; they believe that obedience to Muhammad means obedience to the Quran; some further claim that most hadiths are fabrications (pseudepigrapha) created in the 8th and 9th century AD, and which are falsely attributed to Muhammad. Historically, Mu'tazilites also rejected the hadiths as the basis for Islamic law, while at the same time accepting the Sunnah and ijma. Criticism of ḥadīth has taken several forms. The classical Islamic science of ḥadīth studies was developed to weed out fraudulent accounts and establish a "core" of authentic (i.e., "sound" or ṣaḥīḥ) ḥadīth compiled in classical ḥadīth collections. But some Muslim thinkers and schools of Islam contend that these efforts did not go far enough. Among their complaints is that there was a suspiciously large growth in the number of ḥadīth with each early generation; that large numbers of ḥadīth contradicted each other; and that the genre's status as a primary source of Islamic law has motivated the creation of fraudulent ḥadīth.