On the authority of ʽAbdullāh, the son of ʽUmar bin al-Khaṭṭāb that the Messenger of Allah صلى الله عليه وسلم said:”I have been ordered to fight people until they testify that there is no god but Allah and that Muḥammad is the Messenger of Allah and perform the prayers and give the zakāh. If they do that, they are protected from me regarding their blood and their properties unless by the right of Islam, and their account will be with Allah, the Exalted.”(Narrated by al-Bukhāri and Muslim)Jihād is one of the most important religious duties in Islam and remains so until the Day of Judgement. It is declared by the head of an Islamic state and supported by the community as a whole. It is not aimed at forcing belief on any people, for the Qur’ān ِِّThere shall be no compulsion in religion,”46 i.e., in the acceptance of religion. Rather, its purpose is the removal of obstacles to the propagation of Islam and to free thought and choice in the matter, and then the establishment of a force sufficient to uphold this freedom, insure justice and protect Muslims from persecution and oppression.When the Prophet صلى الله عليه وسلم was commanded by Allah to fight following the hijrah (emigration to al-Madinah) and establishment of the state, Muslims were being persecuted within the Arabian peninsula by the Quraysh and outside its borders by the Persian and Byzantine establishments. Thus, he was to first liberate the Muslims by subduing opposition among the Arabs, then to continue jihād wherever Islam was opposed until men could worship Allah freely and invite others to Islam. The “people”to be fought are those who either attack or persecute Muslims and those who strive to prevent the natural spread of Islam through peaceful means, i.e., through da`wah (invitation) and teaching. They may also include apostates, although this category is usually considered separately under “the right of Islam.” It is known that the Messenger of Allah accepted as a Muslim anyone who pronounced the shahādah and regarded his declaration of faith adequate to protect him from being harmed. He required no immediate proof of the person’s sincerity and thus strongly rebuked Usāmah bin Zayd for killing a man whom he assumed had said “Lā illāh ill-Allāh” only to save himself.
Once a person enters Islam, however, he is expected to fulfill its obligations. A Muslim may be fought by the state for refusing to pray or to give zakāh (unlike fasting and ḥajj), this having been understood by the ṣaḥābah as a part of the “right of Islam.” Hence, with the concurrence of other eminent ṣaḥābah, Abū Bakr fought the 46 Sūrah al-Baqarah, 2:256.