Judaeo-Arabic
In the Middle Ages, Jews in the Islamic diaspora spoke a dialect of Arabic, which they wrote in a mildly adapted Hebrew script (rather than using Arabic script).This phenomenon is called Judaeo-Arabic and may be compared to both Ladino (Judaeo-Spanish) and Yiddish (Judaeo-German).
Some of the most important books of medieval Jewish though were originally written in Judaeo-Arabic, as well as certain halakhic works and biblical commentary. Only later were they translated into medieval scientific Hebrew so that they could be read by the Ashkenazic Jews of Europe. These include:
- Saadia Gaon's Emunot ve-Deot, his Tafsir (biblical commentary and translation), and his siddur (the explanatory parts, not the prayers themselves)
- Solomon ibn Gabirol's Tikkun Middot ha-Nefesh
- Bahya ibn Pakuda's Hovot ha-Levavot
- Judah Halevi's Kuzari
- Maimonides' Commentary on the Mishnah, Sefer ha-Mitzvot, Guide to the Perplexed, and many of his letters and shorter essays.