Islamic Interpretation of Dreams (Ibn-i Sirin):

(Monkey; Primate) A gibbon in a dream represents someone of little intelligence who leads himself to a serious nerve breakdown.

Such a person disrupts his life through his own actions and sins and is despised in people’s eyes.

A gibbon in a dream also represents a toadying person, though proud. He also represents astonishment and forgetfulness.

(Also see Monkey)