He was talking to them about the destruction of Jerusalem, which would
take place in thirty nine years after Jesus had returned to heaven.
This text proves, in Jesus’ own words, that the seventh day Sabbath did
not cease to exist at the cross, any more than the winter ceased to
exist then!
---Because of the sacredness of the Sabbath, the Christians
were to pray that their flight be “not on the Sabbath day.”
4thCommandment.com