신명기 5:17의 주석

ולא תנאף AND THOU SHALT NOT COMMIT ADULTERY — The term ניאוף, “adultery”, is technically only applicable in the case of a married woman.

לא תענה ברעך עד שוא, “Do not testify falsely against your fellow;” The version in Parshat Yitro used the term שקר untrue, false, whereas Moses here appears to expand the prohibition to someone who testifies to something irrelevant, something vain, something which is not enforceable by a court of law, for instance. Frivolous testimony, which may only serve to undermine one of the parties’ good reputation is prohibited by the Torah, also, one of the reasons being that the testimony employs directly or implicitly the name of the Lord. Moses continues with his elaboration, on the tenth Commandment,

The term נאוף (adultery), etc. You might ask: Why does Rashi explain this [commandment] more than the other Ten Commandments? The answer is that Rashi is answering the question: Why is the letter vov in ולא תנאף necessary? Rashi answers: The term “adultery” is applicable only in reference to a married woman. Additionally, the vov indicates that “do not commit adultery” is a continuation of the preceding matter, “Do not murder.” In other words: Be careful with the commandment, “Do not murder,” and through this you will distance yourself from many other transgressions. One [such transgression] is, “Do not commit adultery.” For one [who wishes to commit adultery] will think, “perhaps the husband will not hand over his wife,” and because of this he may commit murder. So too with all [the commandments] mentioned afterwards. See Kitzur Mizrachi for a different explanation.