In 1954, 'Adil al-Ghadban (1905-1972) published a novel entitled Layla al-'Afifa with Dar al-Ma'arif in Cairo.  According to Mahmud Qasim (al-Film al-tarikhi fi al-sinima al-Misriyya), the novel served as the basis for the scenario of Bahiga Hafiz's 1937 film.  So the novel must predate its 1954 publication, but I have not been able to track down an earlier published version.