John Gill Commentary Isaiah 9:4

"For the yoke of his burden, and the staff of his shoulder, the rod of his oppressor, thou hast broken as in the day of Midian." — Isaiah 9:4 (ASV)

For thou hast broken the yoke of his burden Of Galilee, of the nation multiplied, of the spiritual inhabitants of it, whose joy was increased; and this is one reason of it, because they were delivered by the Lord from the burdensome yoke of the ceremonial law, which was broken off and abolished by Christ; and from the tyranny of Satan, the god of this world, out of whose hands they were ransomed and delivered; and from the dominion of sin, under the power of which they had been in bondage.

And the staff of his shoulder, the rod of his oppressor ; different phrases, expressive of the same thing; the bondage and slavery of the law, sin, and Satan:

as in the day of Midian ; when Gideon got an entire victory over the Midianites, with a few unarmed men, by the sound of trumpets, and breaking of pitchers, (Judges 7:16–22) and may denote the easy manner in which Christ obtained a conquest over all his and our enemies; and the means by which it is made known unto us, and we are freed from bondage to spiritual enemies; namely, by the ministration of the Gospel, compared to the blowing of trumpets; and which is a treasure put into earthen vessels, frail and weak men.