You shall not kill anyone whom Allah has forbidden, except for just cause under the law. If anyone is killed unjustly, We have granted the right of retribution to his heir, but let him not carry his vengeance too far in killing the culprit through taking the law in his own hands, as he is supported by the law.
Meaning:-
Retribution: punishment, penalty,
Vengeance: revenge, retribution, retaliation, payback,
Culprit: a person who is responsible for a crime or other misdeed.