Adam Clarke on Matthew 18:25

He had not to pay - That is not being able to pay. As there could not be the smallest probability that a servant, wholly dependent on his master, who was now absolutely insolvent, could ever pay a debt he had contracted of more than 67 millions! - so is it impossible for a sinner, infinitely indebted to Divine justice, ever to pay a mite out of the talent.

Commanded him to be sold - his wife - children, etc. - Our Lord here alludes to an ancient custom among the Hebrews, of selling a man and his family to make payment of contracted debts. See Exo 22:3; Lev 25:30, Lev 25:47; 2Kgs 4:1. This custom passed from among the Jews to the Greeks and Romans. I have already remarked (see Gen 47:19) that in the Burman empire the sale of whole families, to discharge debts, is very common.