أَخْبَرَنَا مُحَمَّدُ بْنُ إِسْمَاعِيلَ، وَإِبْرَاهِيمُ بْنُ الْحَسَنِ، قَالاَ حَدَّثَنَا حَجَّاجٌ، قَالَ قَالَ ابْنُ جُرَيْجٍ أَخْبَرَنِي نَافِعٌ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، 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 رضى الله عنه أَوَلاَ تَبْعَثُونَ رَجُلاً يُنَادِي بِالصَّلاَةِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ يَا بِلاَلُ قُمْ فَنَادِ بِالصَّلاَةِ ‏"‏ ‏.‏

Nafi' narrated that 'Abdullah bin 'Umar used to say: "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 (PBUH) said: 'O Bilal, get up and give the call to prayer.'" Translation Not Available

Book reference: Sunan An Nisai Book 7 Hadith 633
Web reference: Sunan An Nisai Volume 1 Book 7 Hadith 627