Epistula CXXI 3-4

And: Far be it from me to boast except in the cross of my Lord Jesus Christ, through whom the world has been crucified to me, and I to the world. He who has been crucified with Christ despoils the principalities and powers and triumphs over them on the wood. Whence also [in the Gospel according to John], as a type of those who were to believe in the Lord and to be crucified with him, Simon the Cyrenian carries his cross [which, according to other evangelists, he himself carried first].

4. What does it wish to signify, what is written in the same Matthew: "Woe to those who are pregnant and nursing in those days; pray that your flight may not be in winter or on the Sabbath?" — It is manifest that this depends upon what came before. For when the Gospel of Christ has been preached to all nations and the consummation has come and they have seen the "abomination of desolation," which was spoken of by the prophet Danihel Daniel, standing in the holy place, then it is commanded to those who are in Judea to flee to the mountains, and to him who is on the housetop not to descend to take anything from his house, and to him who is in the field not to return to take his tunic. Concerning these things, we have spoken more fully in the commentaries on the same Matthew. And immediately it is joined: Woe to those who are pregnant and nursing in those days. In what days? When the abomination of desolation shall stand in the holy place. There is no doubt that this is preached according to the letter regarding the coming of the antichrist the great adversary of Christ, when the magnitude of persecution compels one to flee and heavy wombs and little nursing infants retard the flight, although some wish to signify the siege and battle of Titus and Vespasian against the Jews and especially Jerusalem. They interpret winter and the Sabbath in this way: that they might not be compelled to flee at that time when the severity of the cold does not allow those fleeing to hide in the fields and in desert places, and the observance of the Sabbath either makes them transgressors if they flee, or makes them subject to the swords of the enemy if they keep the rest and precepts of the Sabbath.