1 Samuel 8:10

According to all the works which they have done since the day that I brought them up out of Egypt even unto this day, wherewith they have forsaken me, and served other gods, so do they also unto thee.

Now therefore hearken unto their voice: howbeit yet protest solemnly unto them, and shew them the manner of the king that shall reign over them.

And he said, This will be the manner of the king that shall reign over you: He will take your sons, and appoint [them] for himself, for his chariots, and [to be] his horsemen; and [some] shall run before his chariots.

And he will appoint him captains over thousands, and captains over fifties; and [will set them] to ear his ground, and to reap his harvest, and to make his instruments of war, and instruments of his chariots.