Book of Mark – The Twelve Disciples

And he went up on the mountain and called to him those whom he desired, and they came to him. And he appointed twelve (whom he also named apostles) so that they might be with him and he might send them out to preach and have authority to cast out demons. He appointed the twelve: Simon (to whom he gave the name Peter); James the son of Zebedee and John the brother of James (to whom he gave the name Boanerges, that is, Sons of Thunder);

Gospel of Mark 3:13-17 ESV

Jesus calls 12 followers of him to be his disciples (or also called apostles). Their task is to be with Jesus and to be sent out to preach and cast out demons. On top of that their number twelve is also similar with the number of the twelve tribes that represented God’s people in the Old testament.

Book of Mark – The Great Crowd

Jesus withdrew with his disciples to the sea, and a great crowd followed, from Galilee and Judea and Jerusalem and Idumea and from beyond the Jordan and from around Tyre and Sidon. When the great crowd heard all that he was doing, they came to him. And he told his disciples to have a boat ready for him because of the crowd, lest they crush him, for he had healed many, so that all who had diseases pressed around him to touch him. And whenever the unclean spirits saw him, they fell down before him and cried out, “You are the Son of God.” And he strictly ordered them not to make him known.

Mark 3:7-12

In contrast of the Pharisees wanting to kill Jesus, there are a great crowd who’s following Jesus. However most of them are just following Jesus just to be healed.

Book of Mark – The Healing on Sabbath

And he looked around at them with anger, grieved at their hardness of heart, and said to the man, “Stretch out your hand.” He stretched it out, and his hand was restored. The Pharisees went out and immediately held counsel with the Herodians against him, how to destroy him.
ESV Mark 3:5-6

Frustrated by their hearts and attitude, for they prefer to insist to hold on tradition and being legalistic rather than letting someone getting healed. For the Pharisees, it’s better to not do good on Sabbath day rather than doing something good on Sabbath. Jesus then healed the man with the withered hand regardless.

The Pharisees reaction? They quickly departed and held counsel with Herod’s people to eliminate Jesus. Do you notice the irony? The Pharisees forbid Jesus to do good on the Sabbath, but they’re actually doing evil thing on Sabbath day instead by planning how to kill Jesus. Truly what Jesus asked was true “Is it lawful on the Sabbath to do good or to do harm, to save life or to kill?”

Book of Mark – The One With Withered Hand

Again he entered the synagogue, and a man was there with a withered hand. And they watched Jesus, to see whether he would heal him on the Sabbath, so that they might accuse him. And he said to the man with the withered hand, “Come here.” And he said to them, “Is it lawful on the Sabbath to do good or to do harm, to save life or to kill?” But they were silent.

Mark 3: 1-4 ESV

The Pharisees seem to be big fan of Jesus :p
They keep following Jesus everywhere and observing what Jesus do very very closely. Unfortunately they’re doing that too find mistakes in what Jesus do so that they can accuse Jesus. And this time they’re trying to find whether Jesus will heal the man with the withered hand or not. For the pharisees, healing is doing work, and doing work on Sabbath day is unlawful for them. However not to heal someone just because it’s Sabbath day, is an act of legalism, which means following the law or tradition just because it’s the law, and can you still call that doing good? That’s why Jesus asked them whether it’s better to do good or to do harm on Sabbath day? To save life or to kill on Sabbath day?

The Pharisees were silent.

Book of Mark – The Lord of Sabbath

And he said to them, “Have you never read what David did, when he was in need and was hungry, he and those who were with him: how he entered the house of God, in the time of Abiathar the high priest, and ate the bread of the Presence, which it is not lawful for any but the priests to eat, and also gave it to those who were with him?” And he said to them, “The Sabbath was made for man, not man for the Sabbath. So the Son of Man is lord even of the Sabbath.”

Mark 2: 25-28 ESV

The Sabbath is given by God for a reminder for human to enter the rest with God. King David overruled the rule in the old testament as Jesus points out by entering the temple and eating the bread of presence during his emergency plight. Jesus claimed that He is the Lord of the Sabbath, because Sabbath was made for mankind for them to actually enjoy the union with God, it’s not a day meant to be filled with strict tradition or a day where mankind judge each other.

Book of Mark – The Law of Sabbath

One Sabbath he was going through the grainfields, and as they made their way, his disciples began to pluck heads of grain. And the Pharisees were saying to him, “Look, why are they doing what is not lawful on the Sabbath?”

Mark 2: 23-24 ESV

Another day, another complain from the pharisees. God gave the Israelite the commandment to celebrate the Sabbath as the rest day in the seventh day. It’s purpose was that the people of God will have that special time to have fellowship with God. It’s a consecrated day for the people of God. However the Pharisees made lots extra rules and made the observance legalistic. That even plucking heads of grain is considered breaking the law of Sabbath.