Classical Arabic is deliberately frozen by religious education while spoken dialects diverge freely.

Evidence

Islamic educational systems have always devoted much effort to preserving knowledge of that form of the Arabic language in which the original revelation of the Koran was vouchsafed to the Prophet Muhammad in the seventh century and to protecting it from change and deformation. Spoken Arabic, like any other language, continues to evolve and to change, nevertheless, so that the various parts of the Arabic-speaking world now have available not only an elevated language that binds the Arab world together but also various vernaculars, some of which have moved so far apart that mutual comprehension between native speakers in the various regions may in some cases not be easily achieved. — L. P. Harvey, Muslims in Spain, 1500 to 1614, 599

Categorization

• XREF: Parallels the deliberate fossilization of liturgical Latin by the Church vs. evolving Romance vernaculars — same diglossia dynamic.