Then he said to them, "The Sabbath was made for man, not man for the Sabbath."
Mark 2:27 (NIV).
According to the Old Testament, God originally established the Sabbath as the celebration of His creative work and as a day of freedom from labor. Israel's miraculous escape from Egypt added another aspect to the Sabbath: the celebration of deliverance from bondage.
Ironically, by the time of Jesus the Sabbath had evolved from a day of freedom to a day of bondage to stringent, exacting rules and regulations. Some of the religious leaders taught that Israel was made for the Sabbath so that the Lord would have someone on earth to keep the Sabbath.
When Jesus declared that the Sabbath was made for man, He was teaching a radical, disturbing concept.
A survey of the New Testament books of Matthew, Mark, Luke and John reveal that Jesus repeatedly challenged those traditional customs by targeting the "mortal danger" rule.
This rule provided an exception to the normal Sabbath restrictions in life-or-death cases. You could use extreme measures to save someone whose life was in danger. But in the case of a chronically ill person, efforts to heal him or her must wait for another day.