John Gill Commentary Mark 3:26

"And if Satan hath rise up against himself, and is divided, he cannot stand, but hath an end." — Mark 3:26 (ASV)

And if Satan rise up against himself
As he must do in such a case as this, if devils are cast out by Beelzebub, the prince of devils:

and be divided ;
one devil against another, as the above calumny supposes;

he cannot stand, but has an end :
his kingdom cannot stand long, but must soon come to an end; his power and authority will soon be destroyed, both over his own species, and among men; (See Gill on Matthew 12:26).