Anas reported; Bilal was commanded to pronounce Adhan in double pairs and IQAMAH in single pairs. Hammam added in his version; “except IQAMAH”. (Using translation from Abū Dāʾūd 508)
«أُمِرَ بِلَالٌ أَنْ يَشْفَعَ الْأَذَانَ وَيُوتِرَ الْإِقَامَةَ إِلَّا الْإِقَامَةَ»