Is owning slaves a sin.

[Esaias]

In the Law, the master of a slave is called "master" and never "owner". Owner is reserved for owners of animals, houses, objects, and for husbands, chief men/leaders, or as a descriptor of mastery of a skill (archers are "owners of arrows", for example).

Master is "adon", owner is "baal"So slaves are not said to have an "owner", just a "lord" or "master".

This distinction appears to hold true throughout the entire Old Testament.