Gregory the Great
Catena Aurea · Matthäusevangelium 24
Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect. Behold, I have told you before. Wherefore if they shall say unto you, Behold, he is in the desert; go not forth: behold, he is in the secret chambers; believe it not. For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be. For wheresoever the carcase is, there will the eagles be gathered together.
(Hom. in Ev. xxxv. i.) Or, because the heart of the elect is assailed with fearful thoughts, yet their faithfulness is not shaken, the Lord comprehends both under the same sentence, for to waver in thought is to err. He adds, If it were possible, because it is not possible that the elect should be taken in error