Then let them who are in Judea flee to the mountains. Having shown by the testimony of the prophet that, when the temple had been profaned, the services of the Law would soon afterwards be abolished, he adds, that fearful and appalling calamities will soon overtake the whole of Judea, so that there will be nothing more desirable than to withdraw a distance from it; and, at the same time, he states that they will be so sudden, that time will scarcely be time allowed for the most rapid flight. For such is the import of the expressions, Let not him who is on the house-top enter into the house; let not him who is in the field turn back; that is, lest, by attempting to save their property, they themselves perish. Again, Woe to the women with child, and to them that give suck; for they will not be in a fit condition for flight. Again, Pray that your fight may not be in the winter; that is, that neither a regard to the sacredness of the day, nor the roughness of the roads, nor the shortness of the clays, may prevent or retard your flight. The design of Christ therefore was, first, to arouse his followers, that they might no longer indulge the hope of ease and repose, and the enjoyments of an earthly kingdom; and, secondly, to fortify their minds, that they might not give way under ordinary calamities. Such an admonition, no doubt, was fir from being agreeable, but, in consequence of their stupidity, and the great weight of the calamities, it was highly necessary.

Then let them - Then Christians may know that the end is come, and should seek a place of safety. Destruction would not only visit the "city," but would extend to the surrounding part of Judea.
The mountains - The mountains of Palestine abound in caves, a safe retreat for those who are pursued. In all ages these caves have been the favorite places of robbers, and they were also resorted to by those in danger, 1-Samuel 13:6; 1-Samuel 22:1; 2-Samuel 23:13; Joshua 10:16. In those mountains they would be safe.

Then let them which be in Judea flee into the mountains - This counsel was remembered and wisely followed by the Christians afterwards. Eusebius and Epiphanius say, that at this juncture, after Cestius Gallus had raised the siege, and Vespasian was approaching with his army, all who believed in Christ left Jerusalem and fled to Pella, and other places beyond the river Jordan; and so they all marvellously escaped the general shipwreck of their country: not one of them perished. See on Matthew 24:13 (note).

Then let them which be in Judea,.... When this signal is given, let it be taken notice of and observed; let them that are in the city of Jerusalem, depart out of it; or who are in any other parts of Judea, in any of the towns, or cities thereof; let them not betake themselves to Jerusalem, imagining they may be safe there, in so strong and fortified a place, but let them flee elsewhere; see Luke 21:21 and accordingly it is observed, that many did flee about this time; and it is remarked by several interpreters, and which Josephus (a) takes notice of with surprise, that Cestius Gallus having advanced with his army to Jerusalem, and besieged it, on a sudden, without any cause, raised the siege, and withdrew his army, when the city might have been easily taken; by which means a signal was made; and an opportunity given to the Christians, to make their escape: which they accordingly did, and went over Jordan, as Eusebius says (b), to a place called Pella; so that when Titus came a few mouths after, there was not a Christian in the city, but they had fled as they are here bidden to
flee into the mountains; or any places of shelter and refuge: these are mentioned particularly, because they are usually such; and design either the mountains in Judea, or in the adjacent countries. The Syriac and Persic versions read in the singular number, "into the mountain"; and it is reported that many of them did fly, particularly to Mount Libanus (c).
(a) De Bello Jude. l. 2. c. 19. sect. 7. (b) Eccl. Hist. l. 3. c. 5. p. 75. (c) Joseph. ib.

Then let them who are in Judea flee to the mountains - So the Christians did, and were preserved. It is remarkable that after the Romans under Cestus Gallus made their first advances toward Jerusalem, they suddenly withdrew again, in a most unexpected and indeed impolitic manner. This the Christians took as a signal to retire, which they did, some to Pella, and others to Mount Libanus.