Mat 18:25 But because as he had not paid, his lord commanded him to be sold, and his wife, and children, and all that he had, and payment to be made.

This analogy (the true meaning of "parable") continues to parallel the ideas about giving and debt from the Lord's Prayer. When we ask God to "give" is our daily bread, the term used for "give" is didômi. The word here to describe the repayment of a debt is apodidômi, or "give back." In the Lord's Prayer, we ask God to give us our daily bread, but then we immediately petition him to forgive the debt this entails because we cannot give anything back to him. What are God's gifts worth? Here, it is made clear that we owe God for our lives, the lives of our families, and everything else we have. This is the "infinite debt" that we can never give back.

Again, remember, what Christ is describing here is the nature of the kingdom of heaven, that is, the universal rule.

"Paid" and "payment to be made" is from apodidômi, which means literally, "give back" or "give up," and also means "restore," "return," "yeild," "give account," and "sell."

"Command" is from keleuô, which means "urge on," "exhort," "order," "command," and "entreat."

"Sold" is from pipraskô, a form of pernêmi which means "to sell," and more specifically, "to export for sale," and often use to apply specifically to slaves, though Matthew and the NT uses it to means any type of sale of goods.