John Gill Commentary Mark 3:22

"And the scribes that came down from Jerusalem said, He hath Beelzebub, and, By the prince of the demons casteth he out the demons." — Mark 3:22 (ASV)

And the Scribes which came down from Jerusalem
Or, "but the Scribes" who had an aversion to Christ, and a different opinion of him: these were they, who having heard much of the doctrine and miracles of Christ, came down from Jerusalem, which lay in the upper, and higher part of the land of Israel, into Galilee, a low country, to make their observations upon him; and take every advantage they could against him, being men, in their way, letter learned, and artful, and cunning: these

said, he has Beelzebub :
or, as the Syriac and Persic versions render it, "Beelzebub is in him": sometimes they call him Beelzebub; sometimes say that he cast out devils by him; and here, that he had him, or was in him; Beelzebub possessed him, and assisted him, and there was a confederacy and familiarity between them:

and by the prince of devils casts he out devils ;
for so they reckoned Beelzebub to be; (See Gill on Matthew 10:25), (See Gill on Matthew 12:24).