What does Luke 6:8 mean?
The Pharisees are lying in wait for Jesus to break the Mosaic law. They are in synagogue and Jesus is teaching. A man with a withered hand is listening. If Jesus heals the man, He will have broken the Sabbath in view of many witnesses. The Pharisees don't realize their position is precarious.First, Jesus knows what they're thinking. Much like the way they quietly judged Jesus for blasphemy when He told the paralyzed man his sins were forgiven (Luke 5:20–22), Jesus perceives their machinations "in his spirit" (Mark 2:8).
Second, Jesus knows this application of the Sabbath law is their own interpretation of the Mosaic law, not the Mosaic law as God provided. The Pharisees' oral law forbids anyone from intentionally straightening a limb because it is too similar to the work of construction. The Mosaic law, itself, isn't nearly so specific.
Third, Jesus knows the heart of God. God gave Israel the Sabbath as a blessing of rest. He did not intend for the Sabbath to be used to hurt or even to avoid doing good to another; "The Sabbath was made for man, not man for the Sabbath" (Mark 2:27). If a person can save a life on the Sabbath—which the Pharisees agreed to—a person can surely heal an ailment (Luke 6:9).