Why did Jesus tell them to pray the flight would not be on the Sabbath?
Jesus told them to pray their flight would not occur on the Sabbath because Jewish believers were so conscious of the Sabbath-law walking limit that most would not dare travel more than about 4,000 feet, not even a mile. On the Sabbath they would not get out of town, making escape impossible.
Les explains that in verse 20 Jesus said, “pray that your flight will not be in the winter, nor on the Sabbath.” Since the Temple had been operating for this first 3 1/2 years, the Jews would be deeply aware of the Sabbath law and how far they could walk without breaking it. Jesus said that if the flight fell on the Sabbath day, most of them would not even dare walk more than about 4,000 feet, which is not even a mile. They would not get out of town. He also says to hope it would not be in winter, because they would be walking and carrying their goods, making it a miserable flight. This fits the time when the Antichrist comes in, defiles the Temple, and turns on the children of Israel, causing that Exodus.