Ioannes Mesue
Ioannes Mesue vel Ioannes filius Mesue, Arabice يوحنا بن ماسويه Yūḥannā ibn Māsawayh (anno 857 mortuus) fuit medicus et scriptor de medicina. Filius fuit Mesuae qui nosocomium Bagdatense condiderat.

Yūḥannā ibn Māsawayh: a Syriac Christian. (Hārūn) al-Rašīd appointed him to translate the ancient medical books that were found in Ancyra, Amorium, and the Byzantine territory after the Muslims had conquered them. He made him the chief translator and put him in charge of skilled scribes who drafted (texts for him). (Yūḥannā) served (the caliphs) Hārūn (al-Rašīd), al-Amīn,55 and al-Maʾmūn,56 and kept this (office) until the days of (the caliph) al-Mutawakkil [i.e., between 232 and 247/847 and 861] (Ibn Ǧulǧul, The Classes of the Physicians and Sages (Ṭabaqāt al-aṭibbāʾ wa-l-ḥukamāʾ), 65.2–5 (ed. Fuʾād Sayyid)).
Yūsuf ibn Ibrāhīm said: Ḥunayn ibn Isḥāq was diligent and keenly interested in learning the art of medicine, but his initial experience in that connection was unfortunate. Yūḥannā ibn Māsawayh gave courses in the subject that were attended by educated persons of every kind. I used to see Ḥunayn ibn Isḥāq, the translator, reading, under Yūḥannā’s guidance, On Sects, the title of which in both Greek and Syriac is ‘harāsīs’ [Peri haireseōn]. At that time, Ḥunayn was constantly asking questions, much to Yūḥannā’s annoyance. Another factor that did not endear him to his teacher was the fact that Ḥunayn came of a family of money-changers in al-Ḥīrah, for the people of Ǧondēšāpūr, and in particular its physicians, looked down on the people of al-Ḥīrah and did not encourage tradesmen’s sons to enter their profession. It so happened one day that Ḥunayn asked Yūḥannā a question about a passage that he had read, which he was having some trouble understanding. Yūḥannā lost his temper. ‘The people of al-Ḥīrah are not fit to learn the art of medicine!’ he said ...
I addressed the hirsute man tentatively: ‘Ḥunayn?’, and he acknowledged that it was indeed he. ‘The son of that whore Risālah,’ he went on, ‘said that no ʿAbādī was capable of learning the art of medicine. May I renounce the Christian religion if I undertake the study of medicine before I have achieved a more comprehensive mastery of the Greek language than anyone else in this age! No one knows about this apart from my brother here, and if it had occurred to me that you might realize who I was, I should have kept out of your way. But now that my disguise no longer deceives you, I must ask you to keep my identity to yourself’ ...
He begged me to use my good offices to effect a reconciliation between himself and Ḥunayn. I was able to bring this about, and from then on Yūḥannā treated Ḥunayn with the utmost respect and generosity, showering him with benefits. I observed this to be the case without interruption until I left Iraq in the year 225/840 (Ibn Abī Uṣaybiʿah, The Best Accounts of the Classes of Physicians (ʿUyūn al-anbāʾ fī ṭabaqāt al-aṭibbāʾ), II/1, 465.2–467.14 (ed. Savage-Smith))

Notae

Bibliographia 
 
 Lutz Richter-Bernburg, "Boḵtīšūʿ" in Encyclopaedia Iranica Online (1989)
 

Medici Syriae
Medici Iracae
Nati saeculo 8 aut 9
Mortui 857