Is it considered a sin to forgive the oppressor who caused the destruction of a person's life and to seek forgiveness for him?

He who forgives someone who has wronged him commits no sin; rather, he is rewarded. Islamic law encourages pardoning and overlooking the faults of those who do wrong. Allah Almighty said: "And if you punish [an enemy], punish with an equivalent of that with which you were harmed. But if you are patient - it is better for those who are patient." And Allah Almighty said: "But whoever is patient and forgives - indeed, that is of the matters [requiring] determination." Forgiving those who do wrong is a path to attaining Allah's forgiveness and pardon. Allah Almighty said: "And let them pardon and overlook. Would you not like that Allah should forgive you? And Allah is Forgiving and Merciful." Furthermore, forgiveness increases a Muslim's honor and dignity.