Sabbath
12 Observe the sabbath day and keep it holy, as the LORD your God commanded you. (Deuteronomy 5:12)
How do we keep the sabbath holy? Contrary to popular opinion, it's unlikely that the Pharisees (in Mark 2) actually believed that Jesus' disciples had done wrong by eating the grain as they walked on the sabbath. It's more likely that they were testing Jesus' understanding of the law. They certainly knew the story of David that Jesus referenced, and they would have understood that need took precedence over the letter of the law. Their anger was very likely caused by Jesus' assertion that he was lord of the sabbath.
Perhaps, then, we would do well to look to Jesus to frame our understanding. On the sabbath Jesus could be found teaching and healing - restoring people to relationship with God and community. He also took up for his disciples who ate because they were hungry. By intentionally seeking to glorify God by ensuring the wholeness of all, we can keep the sabbath holy.
27 Then he said to them, "The sabbath was made for humankind, and not humankind for the sabbath; 28 so the Son of Man is lord even of the sabbath." (Mark 2:27-28)