The construction date of Masjid al-Wakil is unknown, but it is said to have been the oldest mosque in Muscat prior to its demolition in the 1970s. The mosque is likely named for Shihab b. Faysal, who ruled Muscat in the 1950s and 1960s under Sultan Said bin Taymur, wakil translating to deputy or representative; it is possible that the name refers to an earlier deputy of the Al Bu Saids. The original mosque stood opposite Bayt Nadir in Old Muscat and has since been rebuilt.

Source:

Peterson, J. E. Historical Muscat : An Illustrated Guide and Gazetteer. Leiden ; Brill, 2007, 37.