The Cow - 2:178
Believers! Equality in killing is enjoined upon you. Free for free, slave for slave, woman for woman. But whoever is forgiven by the relatives of the deceased, then he must do what is fitting and pay the dowry well. This is a mitigation and mercy from your Lord. Then whoever transgresses after that, for him is a painful torment.
How is the forgiveness of the one to be killed a mercy for the one who forgives?
The Table Spread/5:45
There We commanded them: We commanded them: Life for life, eye for eye, nose for nose, ear for ear, tooth for tooth and wounds for wounds. Whoever gives up this right, He will cover his sins. Those who do not judge by what Allah has revealed are wrongdoers.
The Women/4:149
And if you reveal or conceal a good deed, or forgive an evil deed, Allah is Forgiving, Powerful.