From the web I gathered: "Located at the junction of Abdal Street, Tahal Street and Gül Avenue, the mosque was built by Başçı Ibrahim Efendi in remembrance of Abdal Mehmed, who was a well-known Sufi of the Murad II. era. On top of the rectangular-planned mosque, there are two oval domes. Next to the mosque are a tomb and a water fountain. The mosque has largely been repaired by the Bursa Association of Antique Lovers in 1955."

On the picture: The cenotaph/sarcophagi of Abdal Mehmed.
According to the building inscription, this nice mausoleum (1450) was commissioned by Sultan Murad II himself.

Correspondent: J.M.Criel, Antwerpen.
Source: ‘Vakıf Abideler ve eski Eserler (volume III)’ - Vakıflar Genel Müdürlüğü, Ankara 1983