Breaking the Ten Commandments: How did Joseph know not to have sex with Potiphar's wife, if the Ten Commandments had not already been given? [Exodus 20:1-17]. "The Law"-From the Beginning: I disagree with you about the idea that "the law" was not from the beginning, as was also the Sabbath. [Romans 5:13-14, Romans 7:9, Galatians 3:19].