14 For if you forgive other people when they sin against you, your heavenly Father will also forgive you. 15 But if you do not forgive others their sins, your Father will not forgive your sins
(From NIV Life Application Bible p.2007) “One of the most powerful aspects of the prayer Jesus gave us to use, is this petition. Jesus gives a startling warning about forgiveness: if we refuse to forgive others, God will also refuse forgive us. Why? Because when we don’t forgive others, we are denying our common ground we have as sinners in need of God’s forgiveness. (Remember the prayer says, forgive us “OUR” sins). God’s forgiveness is not the direct result of our forgiving others, but it is based on our realizing what forgiveness means. It is easy to receive forgiveness, but often hard to give it to others. Whenever we ask God for forgiveness, we should also ask, ‘who do I need to forgive?’”
Note: God is not saying that you will only be forgiven if you forgive others. Jesus forgave us all of our sins on the cross before we could do anything. It is by grace you are saved through faith so no one can boast. Jesus is speaking in "hyperbole" here, by saying here is now you live the Christian life. Remember the Sermon on the Mount is how we live in God's kingdom. Therefore, if you have been forgiven and received how can you not forgive others. To not forgive others denies that fact that you have been forgiven.
Who do you need to forgive today as you have already been forgiven for ALL of your sins?
Jesus, we give thanks for your willingly going to the cross, suffering and dying for us. We did not deserve, it but out of love you gave it to us as a gift. Maybe we also likewise forgive those who have sinned against us. Amen.