Major world religion founded by Muhammad in Arabia in the early 7th century CE. The Arabic word islam means "surrender" — specifically, surrender to the will of the one God, called Allah in Arabic. Islam is a strictly monotheistic religion, and its adherents, called Muslims, regard the Prophet Muhammad as the last and most perfect of God's messengers, who include Adam, Abraham, Moses, Jesus, and others. The sacred scripture of Islam is the Qur'an, which contains God's revelations to Muhammad. The sayings and deeds of the Prophet recounted in the sunna are also an important source of belief and practice in Islam. The religious obligations of all Muslims are summed up in the Five Pillars of Islam, which include belief in God and his Prophet and obligations of prayer, charity, pilgrimage, and fasting. The fundamental concept in Islam is the Shari'ah, or Law, which embraces the total way of life commanded by God. Observant Muslims pray five times a day and join in community worship on Fridays at the mosque, where worship is led by an imam. Every believer is required to make a pilgrimage to Mecca, the holiest city, at least once in a lifetime, barring poverty or physical incapacity. The month of Ramadan is set aside for fasting. Alcohol and pork are always forbidden, as are gambling, usury, fraud, slander, and the making of images