John Chrysostom — as excerpted in the Catena Aurea on Matthew 17:19-21

“If you shall ask, Where did the Apostles remove mountains? I answer, that they did greater things, bringing many dead to life. It is told also of some saints, who came after the Apostles, that they have in urgent necessity removed mountainsb. But if mountains were not removed in the. Apostles’ time, this was not because they could not, but because they would not, there being no pressing occasion. And the Lord said not that they should do this thing, but that they should have power to do it. Yet it is likely that they did do this, but that it is not written, for indeed not all the miracles that they wrought are written.”