Located at the base of Jabal Thabeer near Mina, Masjid Al-Bay’ah was named after the pledge (bay’ah) made by the Ansar to Prophet Muhammad (PBUH) in the presence of his uncle, Abbas bin Abdul-Muttalib, in year 13 of Bi’tha (prophethood). The Ansar pledged allegiance to Prophet Muhammad (PBUH) and asked him to migrate to Al-Madinah for support and assistance. This pledge became known as the "Pledge of Al-Aqabah," as it occurred in the mountain pass near Al-Aqabah in Mina. The mosque was built by the Abbasid Caliph Abu Ja'far Al-Mansur in the year 144 AH (761 CE), as indicated by two inscriptions - one on its Qibla wall and another on its southern wall. Another renovation took place under the rule of the Abbasid Caliph Al-Mustansir Bi’llah Abi Ja'far Al-Mansur bin Muhammad Al-Zaher in 625 AH (1227 CE). It has also witnessed several restorations throughout the Islamic Caliphate era. The mosque consists of two arcades (riwaq), each arcade supported by four pillars. It seems that renovations were carried out later. The second arcade is positioned at the end of the mosque, parallel to its northeastern wall. The entrance to the mosque is now located at the northwestern corner, and the Qibla wall has a prominent Mihrab at its center.