Ibn Umar reported: When the Muslims came to Medina, they gathered and sought to know the time of prayer but no one summoned them. One day they discussed the matter. Some of them said: 'Let us adopt a bell like the bell of the Christians.' Others said: 'Or a horn like the horn of the Jews.' Then ʿUmar said: 'Why do you not appoint a man who will call the people to prayer?'The Messenger of Allah (ﷺ) said: O Bilal, get up and summon (the people) to prayer.