"When the Muslims arrived in Al-Madinah they used to gather and try to figure out the time for prayer, and no one gave the call to prayer. One day they spoke about that; some of them said: 'Let us use a bell like the Christians do;' others said, 'No, a horn like the Jews have.' 'Umar, may ,Allah be pleased with him, said: 'Why don't you send a man to announce the time of prayer?' The Messenger of Allah ﷺ said: 'O Bilal, get up and give the call to prayer.'"  

أَنَّهُ كَانَ يَقُولُ كَانَ الْمُسْلِمُونَ حِينَ قَدِمُوا الْمَدِينَةَ يَجْتَمِعُونَ فَيَتَحَيَّنُونَ الصَّلاَةَ وَلَيْسَ يُنَادِي بِهَا أَحَدٌ فَتَكَلَّمُوا يَوْمًا فِي ذَلِكَ فَقَالَ بَعْضُهُمُ اتَّخِذُوا نَاقُوسًا مِثْلَ نَاقُوسِ النَّصَارَى وَقَالَ بَعْضُهُمْ بَلْ قَرْنًا مِثْلَ قَرْنِ الْيَهُودِ فَقَالَ عُمَرُ ؓ أَوَلاَ تَبْعَثُونَ رَجُلاً يُنَادِي بِالصَّلاَةِ فَقَالَ رَسُولُ اللَّهِ ﷺ يَا بِلاَلُ قُمْ فَنَادِ بِالصَّلاَةِ