English translation
607. Narrated Abū Qilāba: Anas رضي الله عنه said, "Bilāl was ordered to pronounce the wording of Adhān twice (in doubles) and of Iqāma once (in singles) only." The subnarrator Ismā'īl said, "I mentioned that to Ayyūb and he added (to that), "Except Iqāma (i.e., Qad-qāmat-iṣ-Ṣalāt which should be said twice)."
