Abdullah ibn Umar reported: When the Muslims came to Medina, they gathered and sought to know the time of prayer, but no one announced it to them. They discussed the matter one day, and some of them said, “Use something like the bell of the Christians,” and some of them said, “Use a horn like that of the Jews.” Umar said, “Why not send a man to call people to prayer?” The Messenger of Allah, peace and blessings be upon him, said, “O Bilal, stand and announce the prayer.”
Source: Ṣaḥīḥ al-Bukhārī 579, Ṣaḥīḥ Muslim 377
Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim
عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ أَنَّهُ قَالَ كَانَ الْمُسْلِمُونَ حِينَ قَدِمُوا الْمَدِينَةَ يَجْتَمِعُونَ فَيَتَحَيَّنُونَ الصَّلَوَاتِ وَلَيْسَ يُنَادِي بِهَا أَحَدٌ فَتَكَلَّمُوا يَوْمًا فِي ذَلِكَ فَقَالَ بَعْضُهُمْ اتَّخِذُوا نَاقُوسًا مِثْلَ نَاقُوسِ النَّصَارَى وَقَالَ بَعْضُهُمْ قَرْنًا مِثْلَ قَرْنِ الْيَهُودِ فَقَالَ عُمَرُ أَوَلَا تَبْعَثُونَ رَجُلًا يُنَادِي بِالصَّلَاةِ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَا بِلَالُ قُمْ فَنَادِ بِالصَّلَاةِ
579 صحيح البخاري كتاب الأذان باب بدء الأذان
377 صحيح مسلم كتاب الصلاة باب بدء الأذان