Treaty of Hudaybiyyah
The Qur'an commands Muslims to make a proper declaration of war prior to the commencement of military operations. Thus, surprise attacks prior to such a declaration are illegal under the Islamic jurisprudence. The Qur'an had similarly commanded Muhammad to give his enemies, who had violated the Treaty of Hudaybiyyah, a time period of four months to reconsider their position and negotiate. This rule, however, is not binding if the adversary has already started the war. Forcible prevention of religious practice is considered an act of war.