What's a Sabbath day's walk? How far were the ancient Jews allowed to walk on a Sabbath?
Exodus 16:29 discouraged long walks on the Sabbath. Traditionally, the limit was 2000 cubits.The calculation seems to be based on a combination of Exodus 16:29 and Numbers 35:5. Or was this based on Joshua 3:4, where 2000 cubits was to be kept between the ark and the people (round trip interpretation)? Or does it come from a narrow view of Numbers 34:5?
Acts 1:12 says the Mount of Olives was a Sabbath day's journey from Jerusalem. I think that may be true if you don't measure from the center of Jerusalem to the top of the Mount of Olives. With this regulation in view, Jesus told his disciples to pray that their flight from Jerusalem (once the Romans were closing in) would not take place on a Sabbath (Matthew 24:20).
The Dead Sea Scrolls uphold the rule, in the Damascus Covenant (CD) 10.14-11.18 which also forbids helping up an animal that has fallen into a pit on the Sabbath (!).