And except the Lord had shortened those days, no flesh would be saved: but for the elect's sake, whom he has chosen, he has shortened the days.
All Commentaries on Mark 13:20 Go To Mark 13
Jerome
AD 420
For our flight is to the mountains, that he who has mounted to the heights of virtue may not go down to the depths of sin.
“Pray that your flight may not be in the winter, or on the sabbath day,” that is, that the fruit of ourwork may not be ended with the end of time; for fruit comes to an end in the winter and time in the sabbath.
But the tribulation shall be great, and the days short, for the sake of the elect, lest the evil of this time should change their understanding.