Medina, the adhan was legislated. When the Companions consulted one another about the best way to alert the people that the time for prayer had begun, some proposed, “Let us light a large fire so everyone will know the time has come.” Others said, “Instead, we should strike the naqus—a clapper like a bell—which the Christians use to summon their worshippers.” A third group suggested, “Rather, we should blow a horn as the Jews do.” The Prophet ﷺ disliked all of these suggestions.

At that point a Companion, ʿAbd Allāh ibn Zayd, came forward. He had seen a man in a dream holding a bell. Ibn Zayd asked him, “Will you sell that?” The man replied, “What will you do with it?” He said, “With it I will announce the prayer.” The man said, “Shall I not direct you to something better than that?” “Certainly,” Ibn Zayd replied. The man then recited to him the words of the adhan and the words of the iqama.

When morning came, Ibn Zayd went straight to the Prophet ﷺ and related his dream. The Prophet said, “This is a true vision.” He then taught the wording to Bilāl, and Bilāl gave the adhan with those familiar words.

Later, during the caliphate of ʿUthmān ibn ʿAffān—may Allah be pleased with him—when the number of worshippers had greatly increased, he introduced a first adhan for Friday, given before the second adhan that is called when the imam arrives. Thus Friday came to have two adhans.

In Ramadan the Prophet ﷺ instructed Bilāl to give an adhan late in the night, near the time for suḥūr, saying, “Bilāl gives the adhan at night to wake the sleeper and to alert the one praying; so eat and drink until you hear the adhan of Ibn Umm Maktūm, for he does not call until dawn breaks.” Consequently the dawn prayer also came to have an earlier, first adhan.