Charles Spurgeon Commentary Mark 5:18-19

"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." — Mark 5:18-19 (ASV)

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

However, Jesus did not allow 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 on you.

This is the third prayer in this chapter. It was not like the two previous ones (the petition of many who were not Christ's followers); rather, it was the earnest supplication of one who was so grateful for what Jesus had done for him that he longed to be always with him. Yet it was not granted, because Jesus saw that the man could serve him better by bearing testimony among those who knew him to the great things the Lord had done for him.