Bede the Venerable — as excerpted in the Catena Aurea on Luke 21:28-33

“He strongly commends that which he thus foretels. And, if one may so speak, his oath is this, Amen, I say unto you. Amen is by interpretation “true.” Therefore the truth says, I tell you the truth, and though He spoke not thus, He could by no means lie. But by generation he means either the whole human race, or especially the Jews.”