"When the Muslims arrived in AI-Madinah, they used to assemble for the Salat, and guess the time for it there was no one who called for it (the prayer). One day they discussed that and some of them said that they should use a bell like the bell the Christians use. Others said they should use a trumpet like the horn the Jews use. But Umar [bin Al-Khattab] said: 'Wouldn't it better if we had a man call for the prayer?'" He said: "So Allah's Messenger said: 'O Bilal! Stand up and call for the Salat.'"
حَدَّثَنَا أَبُو بَكْرِ بْنُ النَّضْرِ بْنِ أَبِي النَّضْرِ، حَدَّثَنَا حَجَّاجُ بْنُ مُحَمَّدٍ، قَالَ قَالَ ابْنُ جُرَيْجٍ أَخْبَرَنَا نَافِعٌ، عَنِ ابْنِ عُمَرَ، قَالَ كَانَ الْمُسْلِمُونَ حِينَ قَدِمُوا الْمَدِينَةَ يَجْتَمِعُونَ فَيَتَحَيَّنُونَ الصَّلَوَاتِ وَلَيْسَ يُنَادِي بِهَا أَحَدٌ فَتَكَلَّمُوا يَوْمًا فِي ذَلِكَ فَقَالَ بَعْضُهُمُ اتَّخِذُوا نَاقُوسًا مِثْلَ نَاقُوسِ النَّصَارَى . وَقَالَ بَعْضُهُمُ اتَّخِذُوا قَرْنًا مِثْلَ قَرْنِ الْيَهُودِ . قَالَ فَقَالَ عُمَرُ بْنُ الْخَطَّابِ أَوَلاَ تَبْعَثُونَ رَجُلاً يُنَادِي بِالصَّلاَةِ قَالَ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَا بِلاَلُ قُمْ فَنَادِ بِالصَّلاَةِ . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ غَرِيبٌ مِنْ حَدِيثِ ابْنِ عُمَرَ .
Tirmizi
The Book on Salat (Prayer) • Hadith 190