Quite a few parts of the Bible don't talk about forgiveness. But quite a few do, and they're not just in the New Testament.
This morning's second reading doesn't mention forgiveness directly, but the verse right after it does.
They all say why forgiving is a good idea.
It's enlightened self-interest, in the long run....
More at A Catholic Citizen in America.
Squeaky Clean, a wealthy but honest businessman, was dissatisfied with life. Although he was a practising Catholic as well as an active member of his parish, God seemed far away. Even worse his inner spirit was withering. When he stumbled on a beautiful farm for sale, he just knew this was God’s answer to his dilemma. Surely a back-to-the-earth lifestyle would bring him closer to God.