Theodosius translated and commented on the
Book of Hierotheos at the request of Lazarus, bishop of
Cyrrhus. His commentary consisted of five books in three treatises, of which the first two treatises were completed at Amida, whilst the third was finished at
Samosata. Although the book had been deemed heretical and repudiated by the Patriarch
Quriaqos of Tagrit as the work of
Stephen Bar Sudhaile in a canonical statement at a synod, Theodosius seems to have accepted its authenticity and makes no mention of Stephen. Theodosius' positive opinion of the book has been noted to reflect the tradition of
mysticism prevalent at the monastery of Qartmin. Theodosius' commentary was later used by Bar Hebraeus in his own commentary on the book, and was also recopied by Abu Nasr of
Bartella in 1290 in a manuscript entitled
On The Hidden Mysteries of the House of God, but only contained half of the commentary (
Za'faran MS. 213). Other surviving works include a medical
syntagma (, "compendium") attributed to Theodosius, as noted by Bar Hebraeus, of which only a fragment survives (Vatican MS. 192). In addition, a
synodical epistle to
Pope Michael III of Alexandria and a
homily for
Lent, both of which are in
Arabic, is preserved (Brit. Mus. MS. 7206). He also wrote a treatise for the deacon George in which he compiled and explained one hundred and twelve maxims (, "symbolic sayings of wise men"), most of which were of
Pythagorean origin that he had translated from Greek into
Syriac; a copy of this treatise in Syriac and Arabic still survives (Paris MS. 157). A few
canons were later also attributed to Theodosius. ==Episcopal succession==