Why did Fredrick Douglass's master start giving him back a small amount of the money from his earnings?

Frederick Douglass's master, Hugh Auld, began giving him a small portion of his earnings as a way to maintain control over him and to symbolize that he was still a slave, even if he was allowed to manage a portion of his own finances. This practice was intended to create an illusion of autonomy while reinforcing the master’s authority. By allowing Douglass to keep some money, Auld hoped to make Douglass more dependent on him while simultaneously preventing him from gaining complete independence or the means to escape.