Charles Ellicott Commentary 1 Samuel 8:12

"and he will appoint them unto him for captains of thousands, and captains of fifties; and [he will set some] to plow his ground, and to reap his harvest, and to make his instruments of war, and the instruments of his chariots." — 1 Samuel 8:12 (ASV)

To ear his ground. —To ear, that is, to plough. The word is an old word (Anglo-Saxon earian), and connected with the Latin arare.