'On the Sabbath' in the Bible

And it happened that Jesus was walking through the grainfields on the Sabbath day and His disciples began picking off heads of grain [to eat] as they traveled along. [Note: It was an accepted custom for people in that day to be permitted to do this as they walked along the paths bordering a grainfield].

And the Pharisees asked Him, "Look, why are they [i.e., Jesus' disciples] doing what is against the law of Moses on the Sabbath day?"

And the Pharisees were watching Him to see if He would heal the man on the Sabbath day, so that they could [find a reason to] accuse Him.

Then He said to the Pharisees, "Is it permissible by the law of Moses to do something good, or something harmful on the Sabbath day? To save a life or to kill it?" But they did not reply.