Islamic Interpretation of Dreams (Ibn-i Sirin):

(Hiding) If one sees himself entering a house to hide in a dream, it means that he will receive condolences, or that he will beget a daughter. Concealment in a dream also means dependence on what one stands behind.

If one hides behind a mountain in a dream, it means placing his trust in a revered or a religious person.

(Also see Clouds)