Gregory the Great — as excerpted in the Catena Aurea on Luke 21:28-33

“(ut sup.) Or else, The heaven and earth shall pass away, &c. As if He says, All that with us seems lasting, does not abide to eternity without change, and all that with Me seems to pass away is held fixed and immoveable, for My word which passeth away utters sentences which remain unchangeable, and abide for ever.”