Jesus said, “Pray that your flight doesn’t take place on the Sabbath or in winter” (Matt. 24:20). Why say this if the Sabbath was to be taken out of the way?
Contextually, Jesus was warning His Jewish disciples about the upcoming destruction of the temple and Jerusalem by Roman armies (Matt. 24:1-34; Lk. 21:20ff). He gave them several signs to watch for and things to pray about so that they would survive this horrendous event, which history tells us took place in the year 70 A.D.
The New Testament books written in the decades between Jesus’ death in 33 A.D. and Jerusalem’s destruction in 70 A.D. make two things very clear. First, the Sabbath, as well as the other laws and practices of Moses’ law, was taken out of the way at the cross and replaced with Christ’s new covenant (Rom. 7:1-4; Eph. 2:14-16; Col. 2:14-16). Second, the majority of the Jews rejected Christ as the Messiah and thus rejected His new covenant, choosing to continue to follow Moses’ law instead (Rom. 1-11).
So by the time Jerusalem was besieged by Rome in 70 A.D., the overwhelming majority of the city’s populace were Jews who still observed the law of Moses, including the Sabbath. The Jews likely kept the gates of the city shut as part of observing the Sabbath (cf. Neh. 13:19). This would mean the Jewish Christians Jesus was warning would not be able to leave the city if the Roman armies showed up to lay siege to the city on a Sabbath. This is why Jesus exhorted them to pray that they wouldn’t have to hastily leave the city on a Sabbath.