Gallus, main protagonist of the Dialogues, says:
These events are now known because Avitianus told them to many people. Besides, recently presbyter Refrigerius, whom you see here, heard the story from Dagridius, a faithful man and a tribune. Under an invocation of divine power, Dagridius swore that Avitianus had told him the story.
(trans. Goodrich 2015: 234, changed by J. Szafranowski)