livbe by the sword, die by the sword

Live by the sword, die by the sword is an ancient proverb coming from the bible that refers to the fact that if you use violence against other people, you can then expect to have violence used against you. In other words, you should expect to become a victim of whatever you use to get what you want. It is another form of an eye for an eye where when you do bad things, you will then have bad things happen to you but in the case of this idiom, bad things will happen in the same form.