Mk 6:7 "And he called the twelve; and began to send them two and two, and gave them power over unclean spirits.
8 And he commanded them that they should take nothing for the way, but a staff only; no scrip, no bread, nor money in their purse,
9 But to be shod with sandals, and that they should not put on two coats.
10 And he said to them: Wheresoever you shall enter into an house, there abide till you depart from that place.
11 And whosoever shall not receive you, nor hear you; going forth from thence, shake off the dust from your feet for a testimony to them.
12 And going forth they preached men should do penance:
13 And they cast out many devils, and anointed with oil many that were sick, and healed them." Rheims NT
There are several things to note about this mission of the twelve.
1. They are amateurs. Their original careers were in one case a tax collector, and perhaps four were fishermen. What the others did is unknown. However there is no indication that they were educated or trained as Rabbis. Jesus merely sends them out trusting in the Father's help.
2. Trust in providence is the real key to what Jesus tells them. For most of us going on a trip we would plan carefully, take enough clothing, make sure we had enough money and places to stay. These "first timers" are to go on foot with only sandals and a walking stick to help. They are not to "call ahead" or make reservations somewhere. They are not to pack a bag, or even take a sake lunch. Even modern missionaries are more careful than this and in fact there has not been anything quite so bold since St. Francis of Assisi.
3. When they get to a village they are to rely on people's generosity and hospitality. Either someone at the village gate or in the town square would invite them home, or after they began preaching in town someone in the crowd would be expected to invite them home for dinner and a place to sleep. It is interesting that once they accept an invitation they are to stay with that family. I suggest that this is a way to ensure honor to the donor. If he is of modest means, and a better offer comes along the preacher would be tempted to move to the better house and more ample or tasty food, but this is disrespectful of the one who first responded with generosity and faith. Believers are not to compete for the honor of housing the apostle nor are the apostles to foster such competition. We are not to worry about money and luxury, nor create divisions among believers, especially over issues of pride or relative wealth. See, Proverbs 16:18, Matthew 6:24, 1 Corinthians 12:25; Romans 16:17;1 Corinthians 1:10.
4. It has been suggested that a tradition existed among the Jews that if they had been traveling outside their homeland and returned, they would shake the dust from their feet when they crossed back into their country. The very dust of gentile land was unclean and should not be allowed to pollute the Holy Land of God's people. Thus when a village would not listen to the message of the Kingdom of God they polluted themselves, became "unclean" which is out of harmony with God, and unworthy to be called God's People.
5. The gospel does not record just how successful they were on this missionary journey, but this is merely the beginning, the first step in taking up their new career. They had been "apprentices" to Jesus and now have become like journeymen, people ready to take the next step but who still had the master available to learn from, who could help with mistakes and encouragement. That they were ultimately successful is clear from you and me who would not have know about the Kingdom or even Jesus without their successful efforts to tell the world.