Is it permissible to perform the call to prayer (Adhan) and the secondary call (Iqama) upon entering a mosque where prayer has already been performed?
Chapter on Adhan
Al-Mughni
Book of Prayer
Primary text
It is permissible for one who enters a mosque where prayer has already taken place to perform the Adhan and Iqama if they wish. This ruling is established by Ahmad, based on the report from Anas who, upon entering a mosque where people had already prayed, commanded a man to give the Adhan and Iqama, and then he led them in a congregational prayer. Alternatively, prayer may be performed without either Adhan or Iqama.
Supporting text
Uruwah stated that the Adhan and Iqama of those who previously prayed suffice for those who arrive later. This view is held by Al-Hasan, Al-Sha'bi, and Al-Nakha'i, although Al-Hasan preferred that the Iqama be performed.