Then Peter came up and said to him, “Lord, how often will my brother sin against me, and I forgive him? As many as seven times?”
Jesus said to him, “I do not say to you seven times, but seventy-seven times." (Matthew 18:21-22)
...is by remembering this.
Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.
(Ephesians 4:32; see also Jesus' story in Matthew 18:22-35)
This, the power of the cross.