Charles Spurgeon Commentary Mark 5:18-20

"And as he was entering into the boat, he that had been possessed with demons besought him that he might be with him. And he suffered him not, but saith unto him, Go to thy house unto thy friends, and tell them how great things the Lord hath done for thee, and [how] he had mercy on thee. And he went his way, and began to publish in Decapolis how great things Jesus had done for him: and all men marvelled." — Mark 5:18-20 (ASV)

And when he had come into the ship, the one who had been possessed by the devil asked him that he might be with him.

However, Jesus did not permit him, but said to him, "Go home to your friends and tell them how great things the Lord has done for you, and has had compassion with you." And he departed and began to proclaim in Decapolis how great things Jesus had done for him; and everyone marveled.

He was told to proclaim what great things the Lord had done for him. He went and proclaimed what great things Jesus had done for him. Did he make any mistake? Oh, no!

It is only another name for the same Person, for Jesus is the Lord. When you speak of him as divine and talk of him in terms fit only for God, you only speak rightly, for he deserves to be praised. And everyone marveled.

So our Lord left them all wondering. Leaving this one messenger to bear testimony to him, he went elsewhere to carry blessings to many others on the other side of the sea. The man appears to have gone through the wide district that bore the name Decapolis. His testimony to the power of Christ was so convincing that when the Saviour revisited that part of the country, he had a very different reception from that which he received on this occasion (See Mark 7:31-37 and Mark 8:1-10).