كتاب الصلاة
2  
The Book of Prayer
Bulugh al-Maram 181
Narrated Anas (RA):
Bilal was commanded to announce the Adhan (each phrase) twice and the Iqamah (each phrase) once except "The prayer stood ready to begin" (to be pronounced twice). [Agreed upon; but Muslim did not mentioned the exception].
وَعَنْ أَنَسِ]بْنِ مَالِكٍ] ‏- رضى الله عنه ‏- قَالَ: { أُمِرَ بِلَالٌ أَنْ يَشْفَعَ اَلْآذَانَ, وَيُوتِرَ اَلْإِقَامَةَ, إِلَّا اَلْإِقَامَةَ, يَعْنِي قَوْلَهُ: قَدْ قَامَتِ اَلصَّلَاةُ } مُتَّفَقٌ عَلَيْهِ, وَلَمْ يَذْكُرْ مُسْلِمٌ اَلِاسْتِثْنَاءَ 1‏ .‏
Reference : Bulugh al-Maram 181
In-book reference : Book 2, Hadith 181
English translation : Book 2, Hadith 181
Bulugh al-Maram 181
A narration of an-Nasa'i has:
"Bilal was ordered by the Prophet (ﷺ)."
وَلِلنَّسَائِيِّ: { أَمَرَ اَلنَّبِيُّ ‏- صلى الله عليه وسلم ‏-بِلَالاً } 1‏ .‏
Reference : Bulugh al-Maram 181
In-book reference : Book 2, Hadith 181
Hadith Text
Reference