مختصر صحيح بخاري
Mukhtasar Sahih Bukhari
Book of Adhan (Call to Prayer)
Saying adhan phrases twice is Sunnah
`Sayyiduna Anas (may Allah be pleased with him) says that Sayyiduna Bilal (may Allah be pleased with him) was commanded to say the Adhan in even (phrases) and the Iqamah in odd, except for "Qad qamatis-salah".
تخریج الحدیث:
