John Malalas (Greek: Ἰωάννης Μαλάλας, Iōánnēs Malálas) was a Byzantine writer who lived around 500 AD. In his Chronicles he records the following story from Constantinople:
“In the 5th of the Indiction such a thing happened: a woman who lived near the Golden Gate was hung up one night, and talked a great deal, so that the crowds in Constantinople came running, and they went away singing hymns to the church of St. Diomedes of Jerusalem, and they brought down the woman from her house and took her to the church of St. Diomedes. She said that after three days the sea would rise and take everything.
All were singing hymns and shouting ‘Lord have mercy.’ It was rumored that many cities had been swallowed up.
At that time in Egypt and Alexandria a plague was occurring. The King sent Narses the cubicularius with light, fast boats and some others to learn what was happening. The children of Narses went as his emissary to St. Diomedes. They learned from the assembled crowd what the woman had said. They came and reported to Narses what was happening in the church, and that they heard from the hanged woman that after three days the sea would rise and drown everything. The crowd heard what she said and went away distraught.”
thanks to Jasmin Hettinger for the tip.