The following is the relationship between sanctions and slavery according to John Thompson:
There were negative sanctions for the slaves. If the slave owner did not treat the slaves decently, then the slaves would not be willing to work for that owner very well. For example, if the slave owner did not dress, feed, treat, etc. the slaves fairly, then the slaves will have less effort to work for that owner. Also there was another thing that was unfair to the slaves. Sometimes they were beaten for no reason, except for the owner to whip them, because they, the owner, felt that they needed to. Also the slaves were whipped excessively after they supposedly did something wrong. Which also means that they were whipped more than what they should have been. For example, John Thompson saw an eight-year old girl whipped until she was bleeding for guess what? For breaking a plate on accident. Even a few slaves said that they would rather die than be whipped.
However, there were positive sanctions for the slaves. If the slave owner treated the slaves with proper clothing, reasonable amount of food, etc. the slaves would have a lot of effort to work decently for that owner. Which would make that owner have a very good crop, place, etc. The slaves had a positive sanction if they were treated badly. They knew that God is a just God and that He would give the bad owner what he deserved. That is what God did, and He still does it today.