(2) باب الأَمْرِ بِشَفْعِ الأَذَانِ وَإِيتَارِ الإِقَامَةِ
Anas reported:
Bilal was commanded (by the Holy Prophet) to repeat the phrases twice in Adhan, and once in lqama. (PT)
Reference (PT): Sahih Muslim 378 d (PT)
In-book reference (PT): Book 4, Hadith 5 (PT)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 739 (PT)