Peter knew well what his master taught about forgiveness. It was especially clear in the model prayer Jesus had taught the disciples: “Forgive us our trespasses as we forgive those who trespass against us.” That was clear enough; yet Peter's question was a very human one: “How far do I have to go in this forgiveness thing?” As an outside limit, he suggests the round number seven. Jesus (teasingly?) responds with the fuller round number seventy times seven—or 490, to be exact. And of course the point was that, like the lawyer who asked Jesus to define “neighbor,” Peter is wrong to inquire into the limits of the command to forgive.
When the king orders the debtor, along with his family and property, to be sold to recover a little of the debt, our debtor begs for mercy and make the absurd promise that he will pay the debt “in full.” The king overlooks the absurdity, allows himself to be moved by compassion, and forgives the man outright.
Still in the flush of what we must imagine would be a feeling of unexpected good fortune and gratitude, this liberated debtor runs into a coworker who owes him a mere hundred denarii (which comes to one millionth of what he had just been forgive—in case Peter is still trying to imagine 490 instances of forgiveness). And the man has the gall to demand immediate payment. When the coworker pleads with our forgiven debtor in the very words he had just used before the king, the man has him committed to the debtors’ prison. Knowing of the first man’s recent benefit, the other servants are rightly enraged, as is the king, when he finds out.
Jesus’ (satiric) numbers game answering Peter’s (misguidedly serious) numbers game is there for us to contemplate, if we dare to measure how much the Lord would have us forgive one another.