Anas said, "Bilal was ordered to pronounce the wording of Adhan twice and of Iqama once only." The sub narrator Ismaʿil said, "I mentioned that to Aiyub and he added (to that), "Except Iqama (i.e. Qadqamat- is-salat which should be said twice).  

إِلاَّ الإِقَامَةَ