The Cow - 2:179
In this equality for you is life-saving, O you of understanding, so that you may be protected.
Intent; the punishment for killing is applied to the murderer, and there is no vendetta against the relatives of the murderer:
The Night Journey/17:33
Do not kill unjustly a soul which Allah has forbidden. Whoever is killed unjustly, We have authorized his heirs. Let him not exceed the limit in killing out of revenge, for he has been helped