What does Matthew 18:26 mean?

This parable illustrates why Christians ought to be willing to forgive when others sin against them. He has described a king who is demanding payment for an impossible debt from one of his servants. The man owes 10,000 talents, the equivalent of literally thousands of lifetimes of earning. Jesus chose a huge, unpayable number in order to make His point about forgiveness. Since the man cannot pay, the king has ordered him and his family to be sold into slavery, along with everything he owns. The amount the king would get for this would not add up to a drop in the bucket of the servant's debt. Still, the king would get something (Matthew 18:23–25).

Now the servant falls on his knees before the king and begins to beg the king for patience. He promises to pay back the money if given enough time. Given the amount owed, however, everyone listening to Jesus tell this story would have understood that to be absurd. The servant's promise was empty and hopeless. The king in the story understands this, as well.