Forgive and you will be forgiven.
“Stop judging and you will not be judged. Stop condemning and you will not be condemned. Forgive and you will be forgiven.” Luke 6:37
“If you forgive others their transgressions, your heavenly Father will forgive you. But if you do not forgive others, neither will your Father forgive your transgressions.” Matthew 6:14-15
Jesus knew a thing or two about motivation. I believe He was pretty serious about us paying attention to this command. I am likely to pay attention if a command is directly linked to how I will be treated, especially if it involves my eternal destiny. This is pretty clear. Jesus was not saying we earn our salvation by forgiving others. He was saying that our attitude toward others is an evidence of the attitude that is required to receive forgiveness: humility. If we truly recognize our unworthiness before Him then when we receive His mercy and grace, we will be grateful. We will also recognize that others deserve mercy and grace just as much as we did, and seek to see that they get it.