Syriac writing containing the legendary correspondence between Jesus and King Abgar of Edessa, the report of the apostle Addai’s mission to Edessa and of the city’s christianization, and the story of the finding of the Cross by Protonike, the wife of emperor Claudius. Towards the end, the text claims to have been written by Labubna, the king’s scribe, and to have been deposited in the royal archives at Edessa.

An earlier and shorter version of part of this story exists in the first book (I,13) of the Greek Ecclesiastical History of Eusebius of Caesarea (written in the late 3rd and early 4th cent.), who mentions a Syriac document from the archives of Edessa as his source. In Eusebius’s text Addai is known by the name Thaddaios (Thaddeus), and some of the details of the later story, such as the portrait of Jesus, are missing. Eusebius’s account ends after Abgar is healed and Thaddaios is asked to speak to the people of Edessa, a prelude to the city’s conversion. The Ecclesiastical History was translated into Syriac around 400. The exact relationship between Eusebius’s text and the early 5th-cent. Teaching remains somewhat unclear, and several expansions of the Teaching obviously belong to the 4th and 5th cent.

Eusebius’s claim of a written source appears plausible, which implies that the kernel of the story was composed, at the latest, towards the end of the 3rd cent. What is remarkable, however, is the paucity of outside corroboration for this story. In the approximately 100 years between Eusebius’s work and the Teaching, no mention is made of this story in Syriac sources. The complete silence of Ephrem, who spent the last ten years of his life in Edessa, as well as of the Chronicle of Edessa, a mid-6th-cent. composition that includes important information on 4th-cent. Edessa, is particularly striking. The earliest affirmation of the story is by Egeria, who mentions it in her Latin travelogue (383–84). It is only after the Teaching begins to circulate that Syriac sources begin to reference the story.

The origins of the story are difficult to discern. The most plausible theory takes into account the heterogeneous nature of the earliest Christianity in Edessa. In the 2nd and 3rd cent. Edessa was home to many competing groups, as the followers of Marcion, Bardaiṣan, Mani, a ‘proto-orthodox’ group, and others all vied for authority. The story most likely originated inside one of these groups fighting for both supremacy and authenticity. Whatever is the case, the group that later became dominant and represented orthodox Christianity perpetuated the story in order to substantiate its claim as the true faith.

The story’s popularity reveals its importance for later Syriac Christianity. Accordingly, Syriac Christianity could trace its roots all the way back to the apostles and to Jesus himself. Also significant is the connection that the story establishes between Edessa, Antioch, and Rome, thus linking the nascent Edessene church to Christianity in the Roman Empire.

An interesting subplot surrounds the portrait of Christ in the Teaching. While this portrait does not occur in Eusebius, and is only briefly mentioned in the Teaching as a portrait painted by Ḥannan, the tabularius, it later became famous in Byzantine Christianity. From the late 6th cent. onwards, the portrait was said to have been ‘made not by human hands’. In 944, the portrait was taken to Constantinople and became an icon of great importance. There is no trace of it after the sack of Constantinople by the Crusaders in 1204.

The full Syriac text of the Teaching is preserved in one early ms., which was written probably in Edessa around 500 (nowadays in the library of St. Petersburg), while extracts exist in a few other mss. In the 5th cent., the Syriac text was translated into Armenian; in the ensuing centuries the legend became fully part of Armenian historiography. There are also translations into Arabic. From Arabic it found its way into Ethiopic, where it enjoyed great popularity.

See Fig. 2.