In those days he departed to the mountain to pray, and he spent the night in prayer to God. When day came, he called his disciples to himself, and from them he chose Twelve, whom he also named apostles: Simon, whom he named Peter, and his brother Andrew, James, John, Philip, Bartholomew, Matthew, Thomas, James the son of Alphaeus, Simon who was called a Zealot, and Judas the son of James, and Judas Iscariot, who became a traitor. And he came down with them and stood on a stretch of level ground. A great crowd of his disciples and a large number of the people from all Judea and Jerusalem and the coastal region of Tyre and Sidon came to hear him and to be healed of their diseases; and even those who were tormented by unclean spirits were cured. Everyone in the crowd sought to touch him because power came forth from him and healed them all. (Lk 6:12-19)
Jesus went up the mountain and prayed the night through. He wanted to be alone and he wanted to spend his time in prayer to God. The prayer showed that he was doing something that belonged to God. The work that he was about to do was something personal. He needed the approval of God or the support of God. The content of his prayer is not known.
He had many followers. He needed a core team to assist him in his work. He had to choose from among his followers. God chose the twelve tribes of Israel while there were in Egypt. Here Jesus chose twelve to be the founders of the new Israel or the kingdom. The twelve tribes were together formed one nation. The twelve apostles were to represent the twelve tribes who in turn would form one people.
He went about preaching and healing. People flocked to him because they were healed and cured of the evil spirits. The kingdom or the new Israel was to be healed of their illnesses. He was forming a people who were whole, integral, and healthy. In the Old Testament he formed the people who were redeemed from slavery. Jesus was in the process of forming a new Israel.