MORDECAI B. SHABBETHAI (called also Mordecai he-Aruk = "the tall"):
Liturgical poet of the thirteenth century; a native either of Italy or of Greece. His penitential prayers ("seliḥot"), which are remarkable both for their form and for their clear, flowing language, have been incorporated into the German, Roman, and Karaite rituals.
- Zunz, Literaturgesch. pp. 336-338.