The Catechism in Questions & Answers

350. What is the significance of the Seventh Commandment in the Old Testament?

Originally the commandment against stealing applied first and foremost to kidnapping. There the purpose was to protect free men from being kidnapped, sold, or held captive. While it was possible to redress property offences by material compensation (atonement), kidnapping was punished by death in Israel: “He who kidnaps a man and sells him, or if he is found in his hand, shall surely be put to death” (Exodus 21: 16).
The theft of another person’s property was also punishable. The Mosaic Law required compensation: “If a man steals an ox or a sheep, and slaughters it or sells it, he shall restore five oxen for an ox and four sheep for a sheep” (Exodus 22: 1).