(50) باب مَا ذُكِرَ عَنْ بَنِي إِسْرَائِيلَ
Narrated Anas:
The people mentioned the fire and the bell (as means proposed for announcing the time of prayer) and by such a suggestion they referred to the Jews and the Christians. But Bilal was ordered, "Pronounce the words of the Adhan (i.e. call for the prayer) twice and the Iqama once only."
Reference: Sahih al-Bukhari 3457
In-book reference: Book 60, Hadith 124
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 55, Hadith 663