وَعَنْ أَنَسِ]بْنِ مَالِكٍ] رضى الله عنه
قَالَ: «أُمِرَ بِلَالٌ أَنْ يَشْفَعَ اَلْآذَانَ، وَيُوتِرَ اَلْإِقَامَةَ، إِلَّا اَلْإِقَامَةَ، يَعْنِي قَوْلَهُ: قَدْ قَامَتِ اَلصَّلَاةُ»
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).
Bulugh al-Maram 216, Book 2, The Book of Prayer, Hadith 37. 1 min read