Bede the Venerable — as excerpted in the Catena Aurea on Mark 3:19-22

“(ubi sup.) Now there is a great difference between those who do not understand the word of God from slowness of intellect, such as those, who are here spoken of, and those who purposely blaspheme, of whom it is added, And the Scribes which came down from Jerusalem, &c. For what they could not deny, they endeavour to pervert by a malicious interpretation, as if they were not the works of God, but of a most unclean spirit, that is, of Beelzebub, who was the God of Ekron. For ‘Beel’ means Baal himself, and ‘zebub’ a fly; the meaning of Beelzebub therefore is the man of flies, on account of the filth of the blood which was offered, from which most unclean rite, they call him prince of the devils, adding, and by the prince of the devils casteth he out devils.”