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).'"
English reference: Vol. 1, Book 7, Hadith 629
Arabic reference: Book 7, Hadith 635