But pray ye - The destruction was certainly coming. It could not be prevented; yet it was right to pray for a mitigation of the circumstances, that it might be as mild as possible. So we know that calamity is before us; sickness, pain, bereavement, and death are in our path; yet, though we know that these things must come upon us, it is right to pray that they may come in as mild a manner as may be consistent with the will of God. We must die, but it is right to pray that the pains of our dying may be neither long nor severe.
In the winter - On account of the cold, storms, etc. To be turned then from home, and compelled to take up an abode in caverns, would be a double calamity.
Neither on the sabbath-day - Long journeys were prohibited by the law on the Sabbath, Exodus 16:29. The law of Moses did not mention the distance to which persons might go on the Sabbath, but most of the Jews maintained that it should not be more than 2000 cubits. Some supposed that it was 7 furlongs, or nearly a mile. This distance was allowed in order that they might go to their places of worship. Most of them held that it was not lawful to go further, under any circumstances of war or affliction. Jesus teaches his disciples to pray that their flight might not be on the Sabbath, because, if they should not go farther than a Sabbath-day's journey, they would not be beyond the reach of danger, and if they did, they would be exposed to the charge of violating the law. It should be added that it was almost impracticable to travel in Judea on that day, as the gates of the cities were usually closed, Nehemiah 13:19-22.

But pray ye that your flight be not in the winter - For the hardness of the season, the badness of the roads, the shortness of the days, and the length of the nights, will all be great impediments to your flight. Rabbi Tanchum observes, "that the favor of God was particularly manifested in the destruction of the first temple, in not obliging the Jews to go out in the winter, but in the summer." See the place in Lightfoot.
Neither on the Sabbath-day - That you may not raise the indignation of the Jews by travelling on that day, and so suffer that death out of the city which you had endeavored to escape from within. Besides, on the Sabbath-days the Jews not only kept within doors, but the gates of all the cities and towns in every place were kept shut and barred; so that their flight should be on a Sabbath, they could not expect admission into any place of security in the land.
Our Lord had ordered his followers to make their escape from Jerusalem when they should see it encompassed with armies; but how could this be done? God took care to provide amply for this. In the twelfth year of Nero, Cestius Gallus, the president of Syria, came against Jerusalem with a powerful army. He might, says Josephus, War, b. ii. c. 19, have assaulted and taken the city, and thereby put an end to the war; but without any just reason, and contrary to the expectation of all, he raised the siege and departed. Josephus remarks, that after Cestius Gallus had raised the siege, "many of the principal Jewish people, πολλοι των επιφανων Ιουδαιων, forsook the city, as men do a sinking ship." Vespasian was deputed in the room of Cestius Gallus, who, having subdued all the country, prepared to besiege Jerusalem, and invested it on every side. But the news of Nero's death, and soon after that of Galba, and the disturbances that followed, and the civil wars between Otho and Vitellius, held Vespasian and his son Titus in suspense. Thus the city was not actually besieged in form till after Vespasian was confirmed in the empire, and Titus was appointed to command the forces in Judea. It was in those incidental delays that the Christians, and indeed several others, provided for their own safety, by flight. In Luke 19:43, our Lord says of Jerusalem, Thine enemies shall cast a trench about thee, and compass thee round, and keep thee in on every side. Accordingly, Titus, having made several assaults without success, resolved to surround the city with a wall, which was, with incredible speed, completed in three days! The wall was thirty-nine furlongs in length, and was strengthened with thirteen forts at proper distances, so that all hope of safety was cut off; none could make his escape from the city, and no provisions could be brought into it. See Josephus, War, book v. c. 12.

But pray ye that your flight be not in the winter, neither on the (h) sabbath day:
(h) It was not lawful to take a journey on the sabbath day; Josephus, book 13.

But pray ye that your flight be not in the winter,.... When days are short, and unfit for long journeys, and roads are bad, and sometimes not passable, through large snows, or floods of water; and when to dwell in desert places, and lodge in mountains, must be very uncomfortable: wherefore Christ directs to pray to God, who has the disposal of all events, and of the timing of them, that he would so order things in the course of his providence, that their flight might not be in such a season of the year, when travelling would be very difficult and troublesome. Dr. Lightfoot observes, from a Jewish writer (h), that it is remarked as a favour of God in the destruction of the first temple, that it happened in the summer, and not in winter; whose words are these:
"God vouchsafed a great favour to Israel, for they ought to have gone out of the land on the tenth day of the month Tebeth; as he saith Ezekiel 24:2 "son of man, write thee the name of the day, even of this same day": what then did the Lord, holy and blessed? If they shall now go out in the winter, (saith he,) they will all die; therefore he prolonged the time to them, and carried them away in summer.''
And since therefore they received such a favour from him at the destruction of the first temple, there was encouragement to pray to him, that they might be indulged with the like favour when Jerusalem should be besieged again:
neither on the sabbath day: the word "day" is not in the Greek text; and some (i) have been of opinion, that the "sabbatical year", or the seventh year, is meant, when no fruits would be found in the fields, and a great scarcity of provisions among people; who would not have a sufficiency, and much less any to spare to strangers fleeing from their native places; but rather the sabbath day, or "day of the sabbath", as the Persic version reads it, is designed; and Beza says, four of his copies read it in the genitive case: and so four of Stephens's. And the reason why our Lord put them on praying, that their flight might not be on the sabbath day, was, because he knew not only that the Jews, who believed not in him, would not suffer them to travel on a sabbath day more than two thousand cubits; which, according to their traditions (k), was a sabbath day's journey; and which would not be sufficient for their flight to put them out of danger; but also, that those that did believe in him, particularly the Jerusalem Jews, would be all of them fond of the law of Moses, and scrupulous of violating any part of it, and especially that of the sabbath; see Acts 21:20. And though the Jews did allow, that the sabbath might be violated where life was in danger, and that it was lawful to defend themselves against an enemy on the sabbath day; yet this did not universally obtain; and it was made a question of, after the time of Christ, whether it was lawful to flee from danger on the sabbath day; of which take the following account (l).
"Our Rabbins teach, that he that is pursued by Gentiles, or by thieves, may profane the sabbath for the sake of saving his life: and so we find of David, when Saul sought to slay him, he fled from him, and escaped. Our Rabbins say, that it happened that evil writings (or edicts) came from the government to the great men of Tzippore; and they went, and said to R. Eleazar ben Prata, evil edicts are come to us from the government, what dost thou say? "shall we flee?" and he was afraid to say to them "flee"; but he said to them with a nod, why do you ask me? go and ask Jacob, and Moses, and David; as it is written, of Jacob, Hosea 12:12 "and Jacob fled"; and so of Moses, Exodus 2:15 "and Moses fled"; and so of David, 1-Samuel 19:18 "and David fled, and escaped": and he (God) says, Isaiah 26:20 "come my people, enter into thy chambers".''
From whence, it is plain, it was a question with the doctors in Tzippore, which was a town in Galilee, where there was an university, whether it was lawful to flee on the sabbath day or not; and though the Rabbi they applied to was of opinion it was lawful, yet he was fearful of speaking out his sense plainly, and therefore delivered it by signs and hints. Now our Lord's meaning, in putting them on this petition, was, not to prevent the violation of the seventh day sabbath, or on account of the sacredness of it, which he knew would be abolished, and was abolished before this time; but he says this with respect to the opinion of the Jews, and "Judaizing" Christians, who, taking that day to be sacred, and fleeing on it unlawful, would find a difficulty with themselves, and others, to make their escape; otherwise it was as lawful to flee and travel on that day, as in the winter season; though both, for different reasons, incommodious.
(h) Taachuma, fol. 57. 2. (i) Vid. Reland. Antiq. Hebrews. par. 4. c. 10. sect. 1. & Hammond in loc. (k) Maimon. Hilch. Sabbat, c. 27. sect. 1. (l) Bemidbar Rabba, sect. 23. fol. 231. 4.

Pray ye that your flight be not in the winter - They did so; and their flight was in the spring. Neither on the Sabbath - Being on many accounts inconvenient; beside that many would have scrupled to travel far on that day. For the Jews thought it unlawful to walk above two thousand paces (two miles) on the Sabbath day.