Bede — on Rev 2:10 (Commentary on Revelation)

“And you will have tribulation ten days. This signifies the whole time in which the necessary commandments of the Decalogue are present. For as long as you follow the light of the divine word, it is necessary to endure the prison of the adversarial enemy. Some understand the ten persecutions of the nations from Caesar Nero to Diocletian to be signified.”