Jesus I know - His power to cast out devils I know. Compare Matthew 8:29.
Paul I know - Paul's power to cast out devils, Acts . Acts 19:12.
But who are ye? - What power have you over evil spirits? By what right do you attempt to expel them? The meaning is, "You belong neither to Jesus nor Paul, and you have no right or authority to at tempt to work miracles in the name of either."

Jesus I know, and Paul I know - In the answer of the demoniac, the verb in varied: τον Ιησουν γινωσκω, και τον Παυλον επιϚαμαι· ὑμεις δε τινες (τινος) εϚε. I acknowledge Jesus, and am acquainted with Paul; but of whom are ye? Ye belong to neither; ye have no authority. And he soon gave them full proof of this. This distinction is observed in my old MS. Bible: I have knowe Jesu, and I wote Poule; forsothe who ben yee.

And the evil spirit answered and said,.... The Alexandrian copy, the Vulgate Latin, Syriac, and Ethiopic versions, add, "to them"; to the seven sons of Sceva:
Jesus I know; to be the Son of God and Messiah, and own that he has power of dispossessing spirits, of which there were many instances in the days of his flesh:
and Paul I know; and own to be a servant of the most high God, by whom miracles of this kind have been wrought:
but who are ye? you are not the disciples of Jesus, nor the servants of God, but the children of the devil, and have no power over us, but on the other hand are subject to us.

the evil spirit answered, Jesus I know--"recognize."
and Paul I know--"know intimately," in contrast to them, whom he altogether disowns.
but who are ye?