Mark describes the process Jesus used to call his first disciples in 1:16–20. Jesus summoned four fishermen and immediately they left their fishing boats and pointed their lives in a new and challenging direction called discipleship. In today's Gospel the number of disciples has increased to 12. Jesus is going to authorize and empower them to assist him in the work of proclaiming the good news in word and by deed.
1) Summoning the Twelve. At no point in the Gospel of Mark does Jesus indicate that his mission is to be carried out by himself alone. From the very beginning Jesus' ministry was to be collaborative. He sends them out two by two, which constitutes them as valid witnesses to the message they will proclaim. Jesus himself authorizes these disciples and empowers them to proclaim the word and confront unclean spirits. In other words the disciples extend the work of Jesus himself by doing what he does.
2) Travel light. There is a certain urgency to the work of discipleship. Baggage must be kept to a minimum: a walking stick, no food, no sack, no money, sandals and no second tunic. This does not mean that the disciples are to be destitute. They must rely on the hospitality of the people to whom they are ministering. They must have the kind of faith that persuades them that God will provide what is needed for this very important work. The disciple must be free to focus on the task at hand, one that cannot be done with lots of baggage to manage.
3) Stay put. The disciples are randomly to enter a house and stay there until it is time to leave. They are not to shop around for the best accommodations. They are to accept whatever is available. If the disciples' presence or message is not welcome they are not to engage in arguing or disputes. They are simply to move on to the next place. As they depart they are to symbolically express their departure by shaking the dust from their sandals. This was a gesture pious Jews would perform when returning home from gentile territory. The disciples do as Jesus instructed and the result is success. The word was proclaimed, demons expelled, and the sick cured. The only resource they had was the authority they received from Jesus.