Mark 5:18-20

18As Jesus was getting into the boat, the man who had been demon-possessed begged to go with him. 19Jesus did not let him, but said, “Go home to your own people and tell them how much the Lord has done for you, and how he has had mercy on you.”

20So the man went away and began to tell in the Decapolis That is, the Ten Cities how much Jesus had done for him. And all the people were amazed.