Jesus appoints the Twelve with a double assignment: “to be with him, and to be sent out to preach.” They must be with him in order to get to know him; in order to attain that intimate acquaintance with him that could not be given to the “people”—who saw him only from the outside and took him for a prophet, a great figure in the history of religions, but were unable to perceive his uniqueness (cf. Mt 16:13ff.). The Twelve must be with him so as to be able to recognize his oneness with the Father and thus become witnesses to his mystery.
Jesus appoints 2 tasks to his disciples, a) To be with him, and b) to preach his message. He needs them to be around him so they can continuously affirm and know that he is the true Son of God; he is more than a prophet or great historical figure.