Bp. of Mardin ; metropolitan bp. of Nisibis ; author, mostly writing in Arabic. He originated from the Nisibis region. He first became bp. of Mardin under the name Yawsep, and took the name Ishoʿyahb when he became ‘metropolitan bp. of Nisibis and Armenia’ (after the E.-Syr. metropolitan see of Khilat had been given up and added to Nisibis). Wright assumes that he became bp. of Nisibis in 1190; as bp. of Nisibis he is attested under Cath. Sabrishoʿ IV (1222–25); he must have died before 1233 (Teule 2006, 246).
While still bp. of Mardin, he wrote a metrical tract on points, ‘Net of points’ (Mṣidtā d-nuqze), divided in eight sections, which in mss. is often transmitted alongside the grammatical works of Eliya of Nisibis and Yoḥannan bar Zoʿbi (e.g., ms. Brit. Libr. Add. 25,876: Wright, Catalogue, vol. 3, 1175a–1179a). A further grammatical work on Syriac, ‘Elucidation in Syriac grammar’ (Manhrānuthā ba-grammaṭiqi suryāytā) is in two columns, Syr. and Arabic (e.g., ms. Paris, 370: Briquel Chatonnet, Manuscrits syriaques, 43–4; and Tübingen, Ms. or. Quart. 1050: Assfalg, Syrische Handschriften, 106–8). His other works, mostly of theological or polemical content, as well as his letters are in Arabic, often with introductory formulas in Syriac. Some of his Arabic works exhibit knowledge of Arabic philosophy (Teule 2006).