Joseph's brothers did him much wrong by selling him to the Ishmeelite traders going to Egypt. We could understand if Joseph was the bitter and angry one. We could understand if he wanted revenge.
After Jacob died in Genesis chapter 49 Joseph's brothers got nervous.They sent a messenger to ask Joseph for forgiveness. When Joseph heard this he wept because he had already forgiven them (Gen 50:17). In verse 18 Joseph's brothers went and bowed down before him to display remorse and they probably had doubts as to Joseph's forgiveness.
In verses 19-21 Joseph assures them that even though they meant it for evil God meant it for God. Then Joseph comforts them. That seems odd. Joseph was the one who was wronged and yet he's he is doing the comforting to those who hurt him. Not only that but he spoke kindly to them.
That is forgiveness. Forgiveness doesn't need a pound of flesh but can see God's hand even in the injustices of life. Forgiveness sees God as bringing good to pass while others mean us harm.
May we learn to forgive as Joseph did.