What does the disciples' prayer in Matthew teach about forgiving others?
According to the context, the disciples' prayer in Matthew teaches that a person must forgive everyone before they themselves can be forgiven. This is a conditional requirement: forgiveness from God is contingent on first extending forgiveness to others. In other words, the prayer makes human forgiveness a precondition for receiving divine forgiveness.
Les explains that this is what the disciples' prayer says back in Matthew: you have to forgive everybody before you can be forgiven. He contrasts this with Paul's teaching in Ephesians 4:32, where Paul tells believers to be kind to one another, tenderhearted, forgiving one another, not so that they can be forgiven, but because they have already been forgiven. Les points out the vast difference: Paul says be ready to forgive your neighbor because you have already been forgiven, even as God in Christ's sake has forgiven you.