A 9th century patriarch of the Eastern church.
He wrote a letter to Sergius, Metropolitan (Archbishop) of Elam, that references a large number of Hebrew manuscripts found in a cave near Jericho. Before the Dead Sea Scrolls discovery, mentions of manuscript finds in the Holy Land were rare.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Texts and Manuscripts of the Old Testament by Mark R. Norton, Page 160)