At the very beginning of the book Mr. Shelby, an unusually kind slave owner, is in debt and planning to sell one of his slaves because he needs the money. At first he only plans to sell one slave, although it is his favorite, Tom. The man he is selling to is a fellow slave owner named Mr. Haley.
During their conversation, Harry actually enters the room. Mr. Shelby then encourages him to sing and dance for Mr. Haley, as he is good at it. Harry does so and is rewarded with some fruit. Mr. Haley is impressed. Just then Harry's mother, Eliza, comes into the room and fetches her son and leaves.
At that point Mr. Shelby tells Mr. Haley that he would like to purchase Eliza, but Mr. Shelby says he cannot possibly part with her. It is at that point that Mr. Haley says he will settle for her son, Harry, instead, and if Mr. Shelby agrees, then all of his debt will be paid.