Brief accounts of Ishoʿyahb's patriarchate are given in the Ecclesiastical Chronicle of the Jacobite writer Bar Hebraeus (floruit 1280) and in the ecclesiastical histories of the Nestorian writers Mari (twelfth-century), ʿAmr (fourteenth-century) and Sliba (fourteenth-century).
A lengthier and more circumstantial account is given in the Chronicle of Seert, an anonymous ninth-century Nestorian history.
This man, after fulfilling his office for fifteen years, set out to visit Nuʿman, king of the Christian Arabs, to try to detach him to the Nestorian faith, as he belonged to our church, but was unable to change his mind.
He died in the tents of the Maʿadaye, and was buried in the monastery of Hind, the daughter of Nuʿman, who dressed him in a monk’s robe.
During his reign the catholicus Ishoʿyahb died, and was succeeded by Sabrishoʿ, who was a native of the village of Pirozabad in the country of Beth Garmai.