those who live by the sword, die by the sword
1. Those who choose a path of violence against others should expect to have violence and harm visited upon themselves. (Often shortened to "live by the sword, die by the sword.") The young men of this city getting caught up in gang violence have the shortest lifespans of anyone in the state. True enough, those who live by the sword, die by the sword.
2. If you rely upon a certain means of doing something, especially that which is illegal, illicit, or harmful to others, you are likely to have a negative outcome as a result thereof. (Often shortened to "live by the sword, die by the sword.") For years, the senator took bribes and skimmed profits from kickbacks all over his state, until finally the FBI launched a sting against him that ended up putting him away for life. Those who live by the sword, die by the sword.