What was the reason behind introducing the second Adhan on Fridays according to the hadith narrated by As-Sa'ib bin Yazid I about Prophet Muhammad (saw)?
 Narrated As-Sa'ib bin Yazid I:                     `Uthman bin `Affan introduced the second Adhan on Fridays when the number of the people in the mosque increased. Previously the Adhan on Fridays used to be pronounced only after the Imam had taken his seat (on the pulpit).