Christ rises above the figures of Moses on the right, Elijah on the left, and John, Peter, and James below. Medallions surrounding the scene depict the other nine apostles and major and minor prophets of the OT. The prominence of Moses and Elijah, along with Peter, James, and John, suggests the mosaic takes its theme from Christ’s transfiguration (Matthew 17:1–8). The mosaic is in the apse of the Church of St. Catherine, Sinai, also built by Justinian in the sixth century.
Achtemeier, P. J., Harper & Row, P., & Society of Biblical Literature. (1985). Harper's Bible dictionary (1st ed.) (1168). San Francisco: Harper & Row.