(6) باب إِفْرَادِ الإِقَامَةِ
'Abdur-Rahman bin Sa'd bin 'Ammar bin Sa'd narrated (from his great-grandfather of the Messenger of Allah) that:
In the Adhan of Bilal, the phrases were two by two, and in his Iqamah they were said once.
Reference: Sunan Ibn Majah 731
In-book reference: Book 3, Hadith 26
English translation: Vol. 1, Book 3, Hadith 731