Detail of the San Vitale Hospitality of Abraham:

The wreath below Jeremiah's name refers to his martyrdom in Egypt reported in Tertullian (Scorpiace, 8). The scroll represents the book of his prophecies; the writing in it is represented by little marks that probably represent letters but could conceivably refer to some belief about his prophecies.

Jeremiah prophesied in the years 627-585 B.C. He is remembered in the Roman Martyrology for May 1 with this notation: "In Egypt [the day of martyrdom of] holy Jeremiah the Prophet. He was stoned to death by the people of Taphnas. According to St. Epiphanius, the faithful used to pray at his tomb and take dust from there by which they were cured of snake bites."1

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Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.

1 My translation. Taphnas is known today as Tell Defenneh.