Sunan Abi Dawud Book 2, Hadith 119
I narrated this tradition to Ayyub who said: “Except IQAMAH”.
Anas reported; Bilal was commanded to pronounce Adhan in double pairs and IQAMAH in single pairs.
Hammam added in his version; “except IQAMAH”.
The words of adhan were pronounced from the time of the Messenger of Allah (ﷺ) twice in pairs (i.e. four times) each, and the words of iqamah were pronounced once in pairs (twice each), except that the phrase "The time for prayer has come" would be pronounced twice. When we heard iqamah, we would perform ablution, and go out for prayer. Shu'bah said: I did not hear AbuJa'far narrating any other tradition except this one.