Jesus called the twelve to him and gave them commission to go to the Children of Israel and do what he had been doing in their presence. He said not to go to the gentiles, but to the House of Israel, the lost sheep of their own people. Their preaching was to be done in the name of the Kingdom of Heaven which was at hand. They were to go in faith and not take extra provisions, nor money.
He told them he was sending them as sheep among wolves. This was dangerous work. Those who heard might not welcome them. They might turn against them, but they were not to retaliate, just shake the dust from their feet and move on.
They were to depend on the Spirit who would speak through them.
If you confess Jesus before men, Jesus will confess you before the Father in heaven.
Later there would be other disciples called to go out and preach and teach. This time he gave them a chance to prove to themselves they were truly called and commissioned. It wasn't the last time, but it gave them a feel for what was coming later.