It was narrated that Ibn 'Umar said:
"At the time of the Messenger of Allah (ﷺ) the phrases of the Adhan were said twice and the phrases of the Iqamah were said once, except that you should I say: 'Qad Qamatis-Salah, Qad Qamatis-Salah (prayer is about to begin, prayer is about to begin).'" (AR)
English reference (AR): Vol. 1, Book 7, Hadith 629 (AR)
Arabic reference (AR): Book 7, Hadith 635 (AR)