Charles Spurgeon Commentary Mark 5:6-7

"And when he saw Jesus from afar, he ran and worshipped him; and crying out with a loud voice, he saith, What have I to do with thee, Jesus, thou Son of the Most High God? I adjure thee by God, torment me not." — Mark 5:6-7 (ASV)

But when he saw Jesus far off, he ran and worshipped him, and cried with a loud voice and said, What have I to do with you, Jesus, you Son of the most high God? I adjure you by God, that you not torment me.

The voice was the voice of the man, but the devil so completely dominated the whole of him, so that he could only speak as the unclean spirit directed him.