Chosen for His Voice, Not His Birth

Bilal ibn Rabah, traditionally credited as the first person to call the adhan, was a formerly enslaved Ethiopian companion of the Prophet, and Islamic tradition treats his selection for this highly visible and honored liturgical role, chosen specifically for the quality of his voice rather than for any social standing, as an early and deliberate demonstration of the new religion's rejection of the tribal and social hierarchies of pre Islamic Arabian society, a point subsequent Islamic teaching and popular retelling has returned to repeatedly as an example of the community's founding egalitarian ideals being enacted in a concrete, visible practice rather than only stated abstractly.

The adhan's wording is not perfectly uniform across all of Islam: the version recited in Shia communities includes an additional phrase after the testimony of faith, affirming Ali as the friend of God, a line absent from the Sunni adhan and reflecting Shia Islam's distinctive theological emphasis on Ali's specific spiritual authority following the Prophet, a variation that means the call to prayer, heard aloud from minarets five times daily across the Muslim world, is itself one of the most publicly audible markers of the Sunni and Shia liturgical difference, recognizable to listeners familiar with both traditions even though the great majority of the call's wording is identical between them.