Is the Thaweb (second call to prayer) permissible outside of Fajr prayer?
Chapter on Adhan
Al-Mughni
Book of Prayer
Primary text
The Thaweb (second call to prayer) is disliked in all prayers other than Fajr, whether the Thaweb is done as part of the Adhan (call to prayer) or after it. This ruling is supported by the narration from Bilal, who stated that the Messenger of Allah, peace be upon him, commanded him to perform the Thaweb for Fajr and forbade him from performing the Thaweb for Isha. Furthermore, the necessity for the Thaweb is specific to the Fajr prayer because it is the time when the general populace is asleep and rises from sleep for prayer, thus necessitating the extra call.
Supporting text
Ibn Umar exited a mosque where he intended to pray upon hearing a man performing the Thaweb during the Adhan for Dhuhr, stating, "Innovation has expelled me."