Worshippers are summoned to prayer by a muezzin, who calls the faithful together by saying:
I testify that there is no god but God (twice)
I testify that Muhammad is God's messenger (twice)
Come to prayer (twice),
Come to salvation (twice)
God is Great (twice)
There is no god but God.
For the dawn prayer, the muezzin adds, after the second "Come to salvation," the phrase "Prayer is better than sleep" twice.
Muslims believe that the call to prayer by the human voice distinguishes Islam from Judaism, which uses the shofar, or ram's horn, and Christianity, which uses the bell. The first muezzin was Bilal, a Black Abyssinian slave who was one of the first converts to Islam.
In addition to the five daily prayers, all male believers are enjoined to gather together on Friday for the noon prayer and listen to a sermon, called a khutba in Arabic, by the leader of the community. The rules for women's attendance at Friday worship have varied over time and place. In many places today, women also attend Friday worship, although they are segregated from the men and pray behind, beside or above them. As the ruler's name is traditionally invoked in the sermon, the khutba became an important sign of the ruler's authority.